absolute encoders 31, 32, 33f

absolute pressure 40

accumulated value  See counters

accuracy, sensor 23, 81–82

thermocouples 82

AC input units 80, 80f

ACK signals 97

AC motors 49

actions, in SFC 165–167, 166f, 166t

actuators 43 See also output devices

ADCs (analog-to-digital converters) 81, 81f

addition 

of binary numbers 68, 70

floating point numbers 71

of data in data registers 284–285

in structured text (ST) 168t

ALARM 103

alarm system example 199f

Allen-Bradley 

ControlNet network 105

Data Highway network (Allen-Bradley) 100, 106

PLC-5 system 13–15, 20, 104–105, 108

example (bundle cutting saw) 314–335

Allen-Bradley ladder diagrams 

addition operation 285f

battery-backed relay circuits 192

conditional jumps 216f

counters 248f, 250f

timers with 252–254, 254f

up-down counters 253f

data movement 281f

greater-than comparison 282f

latch and unlock functions 196f

master control relays 201, 201f

notation for 119, 120f

off-delay timers (TOF) 231, 231f, 232f

on-delay timers (TON) 226–228, 227f

one-shot operation 193f

retentive timers (RTO) 234, 234f

sequencers 256–258, 257t, 258f

shift registers 272f

subroutines 218, 218f

alphanumeric characters, codes for  See ASCII codes

amplifying voltage levels 86–87, 87f, 344f

op-amp comparators 88–89

analog devices, defined 8

analog I/O modules 14

analog signals 79, 81

as output 84, 85

signal conditioning 85–89

changing voltage levels 86–88, 88f

op-amp comparators 88–89

output protection 89

standard 86, 86f

analog-to-digital converters (ADCs) 81, 81f, 82

AND logic gates 120–121, 121f, 132f

functional blocks 133f

instruction lists 157f

instruction lists for 153f

AND operation 

algebra with 135

in structured text (ST) 168t

angular position sensors  See resistive linear and angular position sensors

Apple Firewire bus 94

application development  See program development

application layer (ISO/OSI model) 102

applications of control systems 53–56 See also programs, specific

application storage 313

architecture of PLCs 9–11, 10f

central processing unit (CPU) 7, 9, 12, 79

arithmetic functions 284–285

operations 284–285

arithmetic with binary numbers 68–71

floating point numbers 70–71

one’s and two’s complements 69–70

armature (DC motors) 46–48

ASCII codes 98

examples of 98t

assembler 115

assembly language 115

assignment statements (ST) 167–168

ATN line (IEEE-488) 95, 96t

authoring documentation for PLC systems 313–335

automation tasks 7

auxiliary relays  See internal relays

barrier for car park (example) 352–356

base (floating point numbers) 71

baseband 104

basic relay 1–3, 2f

battery-backed relays 192, 193f

battery failure 313

baud rates 92–93

BCD format 66–67, 280

examples of numbers in 67t

bellows-type pressure sensors 40

bimetal element 33–34, 34f

bimetallic thermostat 341, 342f

binary coded decimal (BCD) format 66–67, 280

examples of numbers in 67t

binary systems 63, 64, 69, 279

arithmetic of 68–71

floating point numbers 70–71

one’s and two’s complements 69–70

signed and unsigned numbers 69

conversion to/from denary system 64

conversion to/from hexadecimal system 66

conversion to/from octal system 65

examples of numbers in 67t

binary words 9 See also bits (data)

bipolar motors 52–53

bistables 73

8-bit registers 267

bits (data) 9, 64, 108, 267, 279–280

parity checks 97

shift registers  See shift registers

sign bit 69

tokens 99

words 9, 71–72, 81, 279

bit storage  See internal relays See also memory; shift registers

Boolean algebra 135–138

Boolean logic 120–126

AND logic 120–121

NAND logic 124–125

NOR logic 125

NOT logic 123–124

OR logic 121–123

in structured text (ST) 168t, 380

truth tables  See truth tables

XOR (exclusive OR) logic 126

Boolean type data 72

BOOLs (Boolean type data) 72

Bosch CAN bus 94

bottle packing program (example) 358–364

bounce, with mechanical switches 26–27

box systems  See brick (single-box) systems

branching 

IL (instruction lists) 155–158

SFCs (sequential function charts) 163–165

brick (single-box) systems 12

I/O addresses 108

broadband 104

brushless DC motors 48–49

built-in switch 27, 28f

Bundle Cutting Saw documentation (example) 314–335

buses 

for parallel communications 94–95

for serial communications 91, 93

bus networks 99, 99f, 100

bytes 108

CAN bus 94

DeviceNet network 105–106

capacitive displacement sensors 38

capacitive proximity sensors 43

capacitive proximity switches 29f, 38f

car park barrier operation (example) 352–356

carrier sense multiple access (CSMA) 100

carrier sense multiple access with collision detection (CSMA/CD) 100, 102

cascaded timers 229f

cascaded TON timers 228–229

CASE statement, in ST 170–171

center roller lever 28

central heating system (example) 344

central processing unit (CPU) 7, 9, 12, 79

chassis, for mounting modules 13–15

checking PLC software 306

circuit diagrams versus ladder diagrams 116

CJP (conditional jumps)  See jump instruction

clocked D latch 73–74, 74f, 74t

clocked JK flip-flops 75, 75f

clocked SR latches 74–75, 74f, 75t

closed loop control 285–289, 286f

modes of control 286–288

coaxial cables 90

coils  See internal relays

collision, data 100

combinational logic systems 63, 72–73

combined modes (closed loop control) 287f, 288

commercial I/O systems, examples of 103–106

commissioning of PLC systems 304–308

simulation 307–308

software-checking 306

testing inputs and outputs 305–306

common voltage supply 85, 85f

communication modules 15

communications interface of PLCs 8

model for 8f

communications paths  See buses

communications systems  See I/O processing

comparing data 282–283

computers versus PLCs 6–7

computer touch pads 30

conditional jumps  See jump instruction

conditional statements 

in pseudocode 296, 297f

in ST 169–171, 380

condition sensors 43

CONNECT 103

constants, defining in ST 173

contactors 44

continuous updating 106

control circuit 2f

control drawing, relay-controlled systems 3–4, 3f

Controller Area Network (CAN) bus 94

DeviceNet network 105–106

controller module 13

controllers 

in distributed networking systems 100

for parallel communications 94

ControlNet network 105

control system applications 53–56 See also programs, specific

control systems design  See designing PLC systems

control task and input sensors 1, 2f

convergence, with SFC 163–165, 164f

conveyor belts 53, 53f

counters with 249

full example program 357–364

bottle packing 358–364

OR gates with 123

packages on, detection of 55–56

tracking items with shift registers 270–272, 274f

count-down underflow (UN) bit 249

counters 245–266

forms of 245

sequencers 254–258

timers with 252–254, 254f

up-down counters 251, 253f, 376–377

count-up overflow (OV) bit 249

CPU (central processing unit) 7, 9, 12, 79

cross roller plunger 28

CSMA (carrier sense multiple access) 100

CSMA/CD (carrier sense multiple access with collision detection) 100, 102

CTD  See down-counters

CTS (clear-to-send) signal 97

CTU  See up-counters

current sinking  See sinking

current sourcing  See sourcing

cycles, PLC 106

in ladder diagrams 117

one-shot operation 193–194

cycle times, PLCs 107, 108

cyclic movement, piston in cylinder (example) 347–348

cyclic redundancy check (CRC) codes 98

cylinders 46, 46f, 47f

DACs (digital-to-analog converters) 84f

Darlington pairs 31

data 71–72

collisions of (in networking) 100

parallel communications 90–91, 94–95, 109

parity checks 97

serial communications 90–94, 109

data communications  See I/O processing

data handling 279–294

arithmetic functions 284–285

operations 284–285

closed loop control 285–289, 286f

data comparisons 282–283

data movement 280–281

data selection 283

Data Highway network (Allen-Bradley) 100, 106

data link layer (ISO/OSI model) 101

data types, defining in ST 172

DAV line (IEEE-488) 95, 95f, 96t

D4CC miniature limit switches 28

DC input units 80, 80f

DC motors 46–48, 48f

dead band 346

debug mode (Telemecanique) 307

decimal system  See denary system

delay-on timers  See on-delay timers (TON)

denary system 63, 280

binary coded decimal (BCD) format 66–67, 280

examples of numbers in 67t

conversion to/from BCD system 67

conversion to/from binary system 64

conversion to/from hexadecimal system 66

conversion to/from octal system 65

examples of numbers in 67t

fixed point numbers 70–71

floating point numbers 70–71

two’s complements 70t

derivative action time 288

derivative mode (closed loop control) 287f, 288

designing PLC systems 295–340 See also program development

desktop consoles 19

detecting faults  See fault finding

DeviceNet network 105–106

D flip-flop 26–27, 27f

diagnostics  See fault finding

diaphragm-type pressure sensors 40

differential amplifiers 87, 87f

digital devices, defined 8

digital I/O modules 14

digital signals 9

converting to/from analog 81, 81f, 82, 84f

defined 8, 79

levels of 10–11, 79

paths for  See buses

sensors for 23

digital systems 63–78

binary system  See binary systems

combinational logic systems 63, 72–73

data  See data

sequential logic systems 63, 73–75

digital-to-analog converters (DACs) 84f

DINTs (double-integer numbers) 71–72

directional control 

motors 48, 48f

valves 44–46, 45f, 46f

discrete signals, defined 79 See also digital signals, defined

displacement sensors 37–38

distributed networking systems 100

division, in structured text (ST) 168t, 169

division operation 284–285

D latch 73–74, 74f, 74t

documentation of PLC systems 313–335

door monitoring 303

double-acting cylinders 46, 46f, 47f

double-integer numbers (DINTs) 71–72

down-counters 245, 246f, 376–377

up-down counters 251, 253f, 376–377

drift 25

drinks machine 367

FBD program 367, 367f

ladder program 367, 368f

drum sequencers 254–258

D101 to D108 lines (IEEE-488) 96t

D-type connectors 91, 92f

dual-channel emergency stop relays 302–303

eddy current proximity switches 29, 29f

electrical conductor 30

emergency stop relays 302–303, 304

emergency stop switches 141, 141f, 302–303

EMF protection 89

encoders 31–33

ENQ/ACK protocol 97

ENQ signals 97

entering programs 129–130

ladder symbols 130

EOI line (IEEE-488) 96t

EPROM (erasable and programming read-only memory) 13, 14t, 15t, 313

with smart sensors 42

equal-to comparison 282

erasable and programming read-only memory (EPROM) 13, 14t, 15t, 313

with smart sensors 42

error-checking in communications 97, 98

serial communications 91

error, sensor 23, 24f

error signal, reacting to  See closed loop control

Ethernet 104–105

exclusive OR  See XOR logic gates

expected value checks 311

exponent (floating point numbers) 71

external relays 187–188

factory-floor networks 106

fail-safe systems 300

fan heater 367–369, 369f, 370f

fault finding 308–313

detection techniques 308–312

program storage 313

FBDs  See function block diagrams (FBDs)

fiber-optic cabling 90

fibre optic sensors 43

field coils 46–48

Firewire bus 94

fixed point numbers 70–71

flags (serial communication bits) 92–93 See also internal relays

flashing light with timers (example) 235, 235f

flip-flops 73, 75, 75f, 194–198, 198f

floating point numbers 70–71, 72

flowcharts, for program development 295–298, 296f

flow controls for serial communications 91

fluid flow meters 41

flyback diodes 89

force sensor, strain gauge as 39–40

forcing, for testing inputs and outputs 305–306, 305f

FOR...DO iteration, in ST 171, 380

forms, controller 1–3

full graphic form, ladder diagrams 118–119

function block diagrams (FBDs) 130–138, 130f, 134f

basic diagramming symbols 131f

example programs 138–141

logic gate blocks 133f

function blocks 

in ST 173–174

symbols for 376–377

function boxes 218–220, 219f

gauge factor 39

gauge pressure 40

GEM-80 PLC 108

General Electric GENET network 100

General-Purpose Instrument Bus 94

GENET network (General Electric) 100

GND line (IEEE-488) 96t

Grafset language 163

Gray code 33

greater-than comparison 282

greater-than-or-equal-to comparison 282

handheld programming devices 19

handshaking 94, 97f

hardware of PLCs 7–8

Hewlett-Packard Instrumentation Bus 94

hexadecimal system 1–3, 64–65, 66

examples of numbers in 67t

hierarchies of communications 100, 100f

high-level languages 115

high sensitive roller plunger 28

holding torque (stepper motors) 51

host networks 99

hybrid stepper motors 51

hysteresis error 23, 24f

I²C bus 94

IEC 61131 standard 17–18, 103

IEC 61131-1 standard 

timers 226f

IEC 61131-1 standard 

sequential function chart 163

IEC 61131-3 programming languages 17

IEC 61131-3 standard 

counters 246f

PID control function 289f

shift registers 272f

IEC 61131-3 standard 379

for battery-backed relay circuits 193f

for function block diagrams 130

for instruction lists (IL) 151, 152t, 157

for ladder diagrams 118–119

one-shot operation 194f

IEC 61131-5 standard 18

IEC 61508 standard 299–300

IEEE-488 bus 94, 95f, 96t

IEEE Project 802 102

IEEE 802.3 standard 102

IEEE 802.4 standard 102

IEEE 1451.4 standard 43

IFC line (IEEE-488) 96t

IF statement, in ST 169, 380

IL (instruction lists) 151–159

branch codes 155–158

code mnemonics 152t

multiple rungs 158

programming examples 159

increment encoders 31, 32f

individual voltage supply 85, 85f

inductive proximity sensors 43

inductive proximity switches 30

inductors, output protection 89

initial values, defining in ST 173

input devices 23–43

encoders 31–33

fluid flow meters 41

liquid-level detectors 28, 41

monitoring system 55, 55f

mechanical switches 26–28, 26f

ladder diagram for (example) 116, 116f

position/displacement sensors 37–38

pressure sensors 40–41

strain gauges as 39–40

proximity switches 29–30

sensors ranges 43

smart sensors 42–43

strain gauges 38–40

differential amplifiers with 87, 88, 88f

temperature sensors 33–37, 283

testing 305

ultrasonic proximity sensors 42

input levels 10–11, 79

input/output units 9–11, 12, 79–85

inputs 

arithmetic operations on 284–285

internal relays with multiple input conditions 188–190

to I/O processing 106–108

in ladder diagrams 117, 128f

sourcing and sinking 11, 79–80, 80f

testing (program development) 305–306

input section of PLCs 8

instruction lists  See IL (instruction lists)

integers (INTs) 71–72

integral action time 288

integral mode (closed loop control) 287f, 288

integrated chip as temperature sensor 342–343

Inter-IC Communication (I²C) bus 94

internal architecture of PLCs 9–11, 10f

central processing unit (CPU) 7, 9, 12, 79

internal relays 187–214, 188f

battery-backed 192, 193f

with ladder programs 188–192

latching programs 190–191

multiple input conditions 188–190

response time 191–192

master control relays 199–204

one-shot operation 193–194, 193f

set-reset function for 197–198

set and reset functions 194–198 See also flip-flops

program examples 198

shift registers  See shift registers

inverters  See NOT logic gates

inverting amplifiers 86–87

I/O addresses 108

I/O modules 14

I/O processing 79–114

commercial systems, examples of 103–106

input/output units 9–11, 12, 79–85

inputs 106–108

networks 99–103

distributed systems 100

standards for 101–103

remote connections 89–98, 89f, 90f

signal conditioning 85–89

changing voltage levels 86–88, 88f

op-amp comparators 88–89

output protection 89

ISO/OSI model 101, 101f

iteration statements, in ST 171–172, 380

JK flip-flops 75, 75f

jump instruction 215–217, 216f

jumps within jumps 216–217, 217f

subroutines 217–220

function boxes 218–220

LAD  See ladder programming (LAD) and ladder diagrams

ladder programming (LAD) and ladder diagrams 20, 115–119, 116f, 134f See also specific company for ladder diagram standards (e.g., Siemens)

arithmetic operations 18

basic diagramming symbols 118–119, 118f, 375

diagramming conventions 117–118

electrical wiring diagrams 20

entering programs 129–130

example programs 138–141

function block diagrams 18

inputs in 117, 128f

instruction lists and 152t, 153–155 See also IL (instruction lists), multiple rungs

multiple rungs 158

internal relays 188–192

latching programs 190–191

multiple input conditions 188–190

response time 191–192

jumping over  See jump instruction

latching relays 127f

logic of  See logic systems (logic gates)

master control relays 200f, 204f, 205f

outputs in 117, 127–129, 128f

SET and RESET coils 195

SFCs (sequential function charts) 18, 162f, 165f

structured text (ST) 18

structured text (ST) versus 174

writing pseudocode and translating 

conditional flow 297, 297f

loops 298, 299f, 300f

sequences 296

ladder symbols 130

last cylinder action, diagnostic program for 312f

last output set (fault detection technique) 309, 310f

latches 73–75

latching relays 44, 127

internal relays for 190–191

layers of ISO/OSI model 101–103

least significant bit (LSB) 64

less-than comparison 282

less-than-or-equal-to comparison 282

lifts 53

light curtains 304

light-emitting diodes (LEDs) 31

limit sensors 43

limit switches 27

linear positioning with stepping motors 49, 49f

linear position sensors  See resistive linear and angular position sensors

linear potentiometers 37

linear variable differential transformers (LVDTs) 37–38, 38f

liquid-level detectors 28, 41

monitoring system 55, 55f

liquid-level switches 28

listeners (parallel communications) 94

LLC (Logical Link Control) layer 102

LM3911N circuit 36f

LM35 package 36f

loading system example 199f

local area networks (LANs) 99

Logical Link Control (LLC) layer 102

logical variables 73

logic systems (logic gates) 63, 73, 120–126, 377–378

Boolean algebra 135–138

combinational 63, 72–73

example programs 138–141

in function block diagrams 130–134

AND logic 120–121, 121f, 132f

functional blocks 133f

instruction lists 157f

instruction lists for 153f

NAND logic 26–27, 27f, 123–124, 124f, 132f

instruction lists for 155f

NOR logic 125, 125f, 132f

functional blocks 133f

instruction lists for 154f

NOT logic 123–124, 123f, 132f

OR logic 121–123, 122f, 132f

functional blocks 133f

instruction lists for 154f

sequential 63, 73–75

symbols for 132f

XOR (exclusive OR) logic 126, 126f, 132f

functional blocks 133f

instruction lists for 155–158

long real numbers (LREALs) 72

loop statements 

in pseudocode 298, 299f, 300f

in ST 171–172

LREAL data (long real numbers) 72

LSB (least significant bit) 64

LVDTs (linear variable differential transformers) 37–38, 38f

machine code 115

machine interlock system 72, 72f

machine language 129

MAC (Media Access Control) layer 102

20 mA loops 94

mantissa 71

manufacturing automation protocol (MAP) 103–104, 104t

Manufacturing Message Service (MMS) 104

MAP (manufacturing automation protocol) 103–104, 104t

markers  See internal relays

mass I/O copying 106–107

master control relays (MCRs) 199–204, 200f

ladder programs for 200f, 204f, 205f

multiple 202–203

program examples 203–204

master networks 99

math, binary  See arithmetic with binary numbers

maximum value, selecting 284f

MCR  See master control relays (MCRs)

measurement error (sensors) 23

mechanical switches 26–28, 26f

ladder diagram for (example) 116, 116f

Media Access Control (MAC) layer 102

MELSEC FX3U compact PLC (Mitsubishi) 13, 13f, 108

MelsecNET network (Mitsubishi) 100

MELSOFT language 19

memory 

for data bits  See registers

program storage 313

memory box 196

memory unit 8

storage capacity of 9

metal resistance strain gauges 38, 39f

microprocessor-controlled systems 4–5 See also programmable logic controllers

minimum value, selecting 284f

Mitsubishi 

MELSEC FX3U compact PLC 13, 13f, 108

MelsecNET network 100

MELSOFT language 19

monitor mode 307

Mitsubishi ladder diagrams 

battery-backed relay circuits 192

conditional jumps 216f

conveyor belt control program (example) 362–363

counters 255t

data movement 281f

greater-than comparison 282f

instruction code mnemonics 152t

AND gates 153f, 157f

NAND gates 155f

NOR gates 154f

OR gates 154f

XOR gates 156f

internal relays with multiple input conditions 189f

master control relays 200

notation for 119

on-delay timers (TON) 226–228, 227f

one-shot operation 193f

shift registers 268, 269, 270f

subroutines 217–218, 218f

valve sequencing program (example) 349–352

car barrier program 354f

inputs and outputs 356

mixing process control program (example) 364–366

MMS (Manufacturing Message Service) 104

mobile phone touch screens 30

modular (rack) systems 13, 16f, 81

I/O addresses 108

monitoring systems 

liquid-level detectors 55, 55f

protected door monitoring 303

monitor mode (Mitsubishi) 307

most significant bit (MSB) 64

sign bit 69

Motorola MPX100AP sensor 25–26, 40

motors 46–49

in distributed networking systems 100

output protection 89

stepper motors 49–53, 49f

stop switch locations 140–141

timers with (examples) 228, 229f, 235, 237f

unipolar versus bipolar 52–53

moving data between locations 280–281

MPX100AP sensor (Motorola) 25–26, 40

MSB (most significant bit) 64

sign bit 69

multiplexers 81, 81f

multiplication operation 284–285

MX100AP pressure sensor 25–26

NAND logic gates 26–27, 27f, 124–125, 124f, 132f

instruction lists for 155f

NC switches 26

in ladder diagrams 118

NDAC line (IEEE-488) 95, 95f, 96t

negated input, in function block diagrams 131f

negative binary numbers  See signed binary numbers

negative transition-sensing coils 194, 194f

nested jumps 216–217, 217f

network layer (ISO/OSI model) 101

networks 99–103

distributed systems 100

standards for 101–103

noninverting amplifiers 87

nonlinearity error 23, 24f

nonvolatile memory 42

NOR logic gates 125, 125f, 132f

functional blocks 133f

instruction lists for 154f

normally closed (NC) contacts 3–4, 43–44

normally closed (NC) switches 26

in ladder diagrams 118

normally open (NO) contacts 3–4, 43–44

normally open (NO) switches 26

in ladder diagrams 118

NO switches 26

in ladder diagrams 118

NOTIFY 103

NOT logic gates 123–124, 123f, 132f

NOT operation 

algebra with 135

in structured text (ST) 168t

NRFD line (IEEE-488) 95, 95f, 96t

NTC semiconductors 35, 35f

number systems  See binary systems See also denary system; hexadecimal system; octal system

octal system 64–65

examples of numbers in 67t

off-delay timers (TOF) 225, 226f, 231–232

Omron 

CP1L 12f

IL code mnemonics 152t

Omron E4C-DS30 ultrasonic proximity sensor 42

Omron E4C-DS80 ultrasonic proximity sensor 42

Omron E4C-DS100 ultrasonic proximity sensor 42

Omron E2F sensor 30

Omron E2K-X capacitive sensor 30

Omron Industrial Automation 28

Omron sensors 42

on-delay timers (TON) 225, 226–230, 226f, 376–377

cascaded 228–229

creating off-delay timers with 231, 231f

on/off cycle timers 230, 230f

sequencing 228

one’s complement 69–70

one-shot operation 193–194

set-reset function for 197–198

on/off cycle timers 230, 230f

on-off mode (closed loop control) 286, 287f

on/off temperature control (example) 346

op-amp comparators 88–89

open systems interconnection (OSI)  See ISO/OSI model

operational amplifier  See amplifying voltage levels

operations, arithmetic 284–285

operators, structured text (ST) 168t, 379–380

optoisolators (optocouplers) 9, 10, 10f, 80

orifice flow meters 41, 42f

OR logic gates 121–123, 122f, 132f

functional blocks 133f

instruction lists for 154f

OR operation 

algebra with 135

in structured text (ST) 168t

OSI  See ISO/OSI model

output devices 43–53

motors  See motors

relays  See relays

output levels 79

RS232 interface 93f

outputs 

changing voltage from sensors 86–88

op-amp comparators 88–89

internal relays with latching circuit 188–190

in ladder diagrams 117, 127–129, 128f

protection of 89

pulse size 84–85

sourcing and sinking 11, 11f, 82–83, 83f

testing (program development) 305–306

output section of PLC system 8

output units  See input/output units

packages on conveyor belt systems, detecting 55–56

parallel branching 163, 164f

parallel communications 90–91, 94–95, 109

parity checks 97

peer-to-peer networks 99

permanent magnet stepper motors 49–50, 50f

personal computers, for programming PLCs 19

phase (stepper motors) 51

Phillips I²C bus 94

photoconductive cells 31

photodiodes 31

photoelectric sensors 43

and switches 30–31, 30f

phototransistors 31

physical layer (ISO/OSI model) 101

PID control 288, 289f

piezoelectric crystals 40

25-pin D-type connectors 91, 92f

pin plunger 28

plastic rod 28

position sensors 37–38

positive binary numbers  See signed binary numbers

positive transition-sensing coils 194, 194f

potential dividers 86, 86f

potentiometers 37, 37f

power (floating point numbers) 71

power supply unit 7

presence sensing sensors 43

presentation layer (ISO/OSI model) 102

present, timer 225

present value, for counters 245, 247

pressure sensors 40–41

liquid-level detectors 28, 41

monitoring system 55, 55f

strain gauges as 39–40

processor unit 7

production lines  See conveyor belts

PROFIBUS DP network (Siemens) 100

Profibus (Process Field Bus) system 106

program development 

commissioning 304–308

simulation 307–308

software-checking 306

testing inputs and outputs 305–306

documentation 313–335

fault finding 308–313

detection techniques 308–312

program storage 313

flowcharts and pseudocode 295–298

safe systems 298–304

emergency stop relays 302–303

safety functions 303–304

safety PLCs 304

programmable logic controllers 

control machines and processes 5–6, 5f

design  See designing PLC systems

PLCs, about 5–7

systems, about 12–15, 20

programming devices 8, 19–20

programming methods  See function block diagrams (FBDs) See also IL (instruction lists); ladder programming (LAD) and ladder diagrams; SFCs (sequential function charts); ST (structured text)

programs for PLCs 16–20

programs, specific 341–374

conveyor belt control 357–364

bottle packing 358–364

process control 364–366

valve sequencing 347–357

car park barrier operation (example) 352–356

controlled cylinder reset 356–357

cyclic movement 347–348

sequencing 348–352

program storage 313

Project 802 (IEEE) 102

proportional mode (closed loop control) 287, 287f

protected door monitoring 303

protocols, communication 91, 96–98

with networking 99, 101–103

proximity switches 29–30

pseudocode 295–298

PTC semiconductors 35

pull-in rate (stepper motors) 52

pull-in torque (stepper motors) 51

pull-out rate (stepper motors) 52

pull-out torque (stepper motors) 52

pulse functions 197–198, 198f

pulse size, output 84–85

pulse timers (TP) 225, 226f, 232–234, 376–377

pulse width modulation (PWM) 46–48, 48f

PWM  See pulse width modulation (PWM)

quantization levels 81

rack systems  See modular (rack) systems

RAM  See random-access memory (RAM)

random-access memory (RAM) 

battery failure and 313

range, sensor 24

RCV block 103

READ block 103

REAL data 72

real numbers 72

reducing voltage levels 86–88, 86f

reed switches 29, 29f

reflective photoelectric sensors 30–31

registers 267, 279–280

moving data between 280–281

relay-controlled systems 3–4, 3f

control red and green lights 4, 4f

versus PLCs 6

relays 10, 43–44, 44f, 83

battery-backed 192, 193f

emergency stop relays 302–303

internal  See internal relays

latching relays 44, 127

internal relays for 190–191

master control relays 199–204

ratchet type 28

reversing motor rotation 48

relay symbols 3–4, 3f

reliability, measurement system 25

remote connections 

ASCII codes 98

examples of 98t

protocols for 96–98

remote I/O modules 89–98, 89f, 90f

REMOTE_VAR 103

REN line (IEEE-488) 96t

repeatability, measurement system 25

REPEAT...UNTIL iteration, in ST 172, 380

replication 311

RESET coils 194–198, 195f See also flip-flops

for one-shot operation 197–198

program examples 198

resetting counters 245, 246f, 249

resistive linear and angular position sensors 37

resistive temperature detectors (RTDs) 34–35

resolution (voltage) 81–82

response speed, PLC 108

response time 

with internal relays 191–192

sensor 24

retentive memory coils 192, 193f

retentive relays 192

retentive timers (RTO) 234

RETURN statement, in ST 174

reversing motor rotation 48

ring networks 99, 99f

rise time, sensor 24

robot control systems 54–55, 54f

Rockwell Automation 28

Allen-Bradley PLC-5 13–15, 20, 104–105

RSLogix language 20

roller-actuated limit switch 27, 28f

roller plunger 28

rotary potentiometers 37, 37f

RS function blocks 220, 220f

RS232 interface 91

RTS and CTS signals 97

RS422 interfaces 93, 93f

RS423 interfaces 93, 93f

RS485 interfaces 106

RSLogix language 20

RTDs (resistive temperature detectors) 34–35

RTO  See retentive timers (RTO)

RTS (ready-to-send) signal 97

rungs  See ladder programming (LAD) and ladder diagrams

SAA 1027 circuit 52–53, 52f

safe systems 298–304

emergency stop relays 302–303

safety functions 303–304

safety PLCs 304

safety interlock switches 43

safety mats 304

SCADA (supervisory control and data acquisition systems) 100

scanning ladder diagrams 117, 117f

scanning time, PLCs 108

internal relay response time 191–192

scientific notation 71

sealed cross roller plunger 28

sealed pin plunger 28

sealed roller plunger 28

secure PLC systems  See safe systems

security 15

selection function blocks 283

selective branching (SFC) 163, 163f

self-testing  See fault finding

semiconductors 35

strain gauges 38–40

differential amplifiers with 87, 88, 88f

semigraphic form, ladder diagrams 118–119

SEND block 103

sensitivity, measurement system 25

sensors  See also switches

changing voltage from 86–88

op-amp comparators 88–89

defined 23

in distributed networking systems 100

liquid-level detectors 28, 41

monitoring system 55, 55f

Omron E2F 30

Omron E2K-X capacitive 30

photoelectric sensors and switches 30–31, 30f

position and displacement sensors 37–38

pressure sensors 40–41

strain gauges as 39–40

response of 24f

smart sensors 42–43

strain gauges 38–40

differential amplifiers with 87, 88, 88f

switch sensors  See mechanical switches

temperature sensors 33–37, 283

ultrasonic proximity 42

sensors ranges 43

sequencer 256–258

control 257

destination 257

file 256

length 257

mask 257

position 257

sequencer output (SQO) 256, 258

sequencers 254–258

sequences, programming 296

sequencing 

with on-delay timers 228

piston movement (example) 348–352

with shift registers 270, 273f

sequential flowcharts 296, 364

sequential function charts  See SFCs

sequential logic systems 63, 73–75

serial communications 90–94, 109

session layer (ISO/OSI model) 102

SET and RESET coils 194–198, 195f See also flip-flops

for one-shot operation 197–198

program examples 198

settling time 24

SFC (SIMATIC S7-Graph) language 19–20

SFCs (sequential function charts) 160–167, 352, 378

actions 165–167, 166f

branching and convergence 163–165

SHIELD line (IEEE-488) 96t

shift registers 267–278, 269f

for keeping track of items 270–272, 274f

in ladder diagrams 268–272

sequencing application example 270, 273f

short-duration pulses 249

short integer numbers (SINTs) 71–72

Siemens 

PROFIBUS DP network 100

Profibus (Process Field Bus) system 106

SIMATIC S7 addressing 108

SIMATIC STEP 7 language 19–20

test mode 307

Siemens ladder diagrams 

addition operation 285f

conditional jumps 217f

subroutine function block 219f

conveyor belt control program (example) 363–364

counters 250f, 253f, 255t

data movement 281f

function block diagrams 134f

greater-than comparison 282f

IL code mnemonics 153

instruction code mnemonics 152t

AND gates 153f, 157f

NAND gates 155f

NOR gates 154f

OR gates 154f

XOR gates 156f

internal relays with multiple input conditions 189f

master control relays 201–202

notation for 119, 120f

off-delay timers (TOF) 231, 231f

on-delay timers (TON) 226–228, 227f

set-reset function 196, 197–198, 198f

shift registers 272f

valve sequencing program (example) 351f

car barrier program 355f

inputs and outputs 356

Siemens S7-1200 system 305–306

signal conditioning 85–89

changing voltage levels 86–88, 88f

op-amp comparators 88–89

output protection 89

signal lamp task example 

instruction lists 159, 159f

ladder diagram 139f

last output set (fault detection technique) 309, 311f

timers for 235, 237f

signal levels 10–11, 79

RS232 interface 93f

sign bit 69

signed binary numbers 69, 71–72

one’s and two’s complements 69–70

SIMATIC S7 addressing (Siemens) 108

SIMATIC STEP 7 language (Siemens) 19–20

simulation 307–308

simultaneous convergence (SFC) 164f

single-acting cylinders 46, 46f, 47f

single-box (brick) systems 12

I/O addresses 108

single highway networks 99, 99f

single pole/double throw (SPDT) switches 26–27

sinking 11

input units 79–80, 80f

output units 82–83, 83f

SINTs (short integer numbers) 71–72

slave networks 99

slew range (stepper motors) 52

slot passing 99

smart sensors 42–43

software for PLCs 19

testing/checking 306

solenoids as actuators 

directional control valves 44, 45f

output protection 89

relays 43–44

sourcing 11

input units 79–80, 80f

output units 82–83, 83f

spool valves 44

SR function blocks 219, 220f

SR latches 74–75, 74f, 75t

SRQ line (IEEE-488) 96t

ST (structured text) 167–174, 379–380

conditional statements 169–171, 380

iteration statements 171–172, 380

ladder diagrams versus 174

operators 168t, 379–380

programs 172–174

stability, measurement system 25

standard communication blocks 103

star networks 99, 99f

STATUS block 103

step angle (stepper motors) 51

stepper motors 49–53, 49f

ST (SIMATIC S7-SCL) language 19–20

stop/start switch, ladder diagram for 116, 116f

stop switches 300–301

emergency stop switches 141, 141f, 302–303

locations of 140–141

storage capacity of memory units 9

storage, program 313

storage tank 365–366, 366f

stored data  See internal relays See also memory

strain gauges 38–40

differential amplifiers with 87, 88, 88f

structured text  See ST (structured text)

subroutines 217–220

function boxes 218–220

subtraction 

of binary numbers 68, 70

of data in data registers 284–285

in structured text (ST) 168t

switches  See also limit switches; logic systems (logic gates); mechanical switches; normally closed (NC) switches; normally open (NO) switches; photoelectric sensors; proximity switches; reed switches; stop switches; thumbwheel switch

testing 305

switching frequency 346

symbols 375–380

synchronization for serial communication 91

system design  See designing PLC systems

system documentation 313–335

talkers (parallel communications) 94

tasks appropriate for control systems 1

Telemecanique 

debug mode 307

SET and RESET coils 195–196

Telemecanique ladder diagrams 

notation for 119, 120f

on-delay timers (TON) 226–228, 227f

set-reset function 195–196, 197–198, 198f

temperature coefficients 33–34, 35

temperature sensors 33–37, 283

testing (program development) 

fault finding 308–313

detection techniques 308–312

program storage 313

inputs and outputs 305–306

software-checking 306

test mode (Siemens) 307

Texas Instruments 

TIWAY network 100

TSL220 sensor 31f

thermistors 35f, 342–343, 343f See also semiconductors

thermocouples 36–37, 36f, 37t, 342–343

accuracy of 82

thermodiodes 35–36

thermostat  See temperature sensors

thermotransistors 35–36

three-track encoders 32, 32f

three-wire circuits 34–35, 34f

thumbwheel switch 280, 280f

time duration data 72

timers 225–244

with counters 252–254, 254f

off-delay (TOF) 225, 226f, 231–232

on-delay  See on-delay timers (TON)

programming examples 235

pulse timers (TP) 225, 226f, 232–234, 376–377

retentive timers (RTO) 234

types of 225

watchdog timers 308

timing checks 308

TIWAY network (Texas Instruments) 100

TOF  See off-delay timers (TOF)

toggles 75

token passing 99

TON  See on-delay timers (TON)

Toshiba ladder diagrams 

counters 255–256, 255t

on-delay timers (TON) 226–228, 227f

sequencers 255–256, 256f

shift registers 269, 271f

Toshiba PLC brick 12

TP  See pulse timers (TP)

tracking items with shift registers 270–272, 274f

traditional control systems 1–3

traffic lights, sequence for 160, 160f

timers for 235, 236f

transducers, defined 23

transistor-type output 10, 83f

transition-sensing coils 194, 194f

transmission rates, serial communications 92–93

transmissive photoelectric sensors 30–31

transparent latches 73–74

transport layer (ISO/OSI model) 102

triac outputs 10, 84f

truth tables 63, 72, 73t

for latches 74

AND logic 120–121

NAND logic 124–125

NOR logic 125

NOT logic 123–124

OR logic 121–123

XOR (exclusive OR) logic 126

TSL220 sensor (Texas Instruments) 31f

tuning 288

twisted-pair cabling 90

two-channel emergency stop relays  See emergency stop switches

two-handed engaging 303

two-position valves 45f

two’s complement 69–70, 279

two-state variables 73

two-step controls 288

two-track encoders 32

TYPE statements, in ST 172

UARTs (universal asynchronous receivers/transmitters) 91

UDINT data 71–72

UINT data 71–72

ULINT data 71–72

ultrasonic proximity sensors 

input devices 42

ultrasonic sensors 43

unipolar motors 52–53

universal asynchronous receivers/transmitters (UARTs) 91

Universal Serial Bus (USB) 94

unsigned binary numbers 69, 71–72 See also signed binary numbers

up-counters 245, 246f, 376–377

up-down counters 251, 253f, 376–377

up-down counters 246f

URCV block 103

USB connections 94

USEND block 103

USINT data 71–72

USTATUS block 103

value checks 311

valve operation program example 

full program 347–357

car park barrier operation (example) 352–356

controlled cylinder reset 356–357

cyclic movement 347–348

sequencing 348–352

instruction lists 159, 159f

ladder diagram 139f

with master control relay 203f

valves 

directional control valves 44–46, 45f, 46f

spool valves 44

4/2 valves 45, 45f

4/2 valves 45, 45f

vampire taps 104

variable reluctance stepper motors 51, 51f

variables, defining in ST 172–173

voltage levels, changing 86–88

washing machine, SFC for 162f

watchdog timers 308

Wheatstone bridges 34–35, 34f

differential amplifiers with 87, 88, 88f

with strain gauges 39, 39f

WHILE...DO iteration, in ST 171–172, 380

words (binary data) 71–72, 81, 279

words (binary words) 9

workplace safety  See safe systems

WRITE block 103

writing documentation for PLC systems 313–335

XON/XOFF protocol 97

XOR (exclusive OR) logic gates 126, 126f, 132f

functional blocks 133f

instruction lists for 155–158

XOR operation 

algebra with 136

in structured text (ST) 168t

zero drift 25