ECT 464 Lecture 5 Modes and Memory

Do the thing you fear and the death of fear is certain. Be strong and courageous. Do not be afraid or terrified because of them, for the LORD your God goes with you; he will never leave you nor forsake you. Deuteronomy 31:6

PLC Modes of Operation Run Run Program Program Troubleshoot Troubleshoot

Program Mode All outputs off All outputs off I/O scan is off I/O scan is off Upload/Download programs from PLC Upload/Download programs from PLC Monitor and Edit programs, ladder logic, rung descriptions Monitor and Edit programs, ladder logic, rung descriptions Set I/O force bits without enables being executed Set I/O force bits without enables being executed

Run Mode Scans Inputs, stores in memory Scans Inputs, stores in memory Scans Rungs, sets outputs in memory Scans Rungs, sets outputs in memory Sets Outputs Sets Outputs

PLC Scan Time The time it takes to complete one complete cycle in run mode. The time it takes to complete one complete cycle in run mode. Can take milliseconds depending on number of rungs in ladder logic Can take milliseconds depending on number of rungs in ladder logic Inputs must stay enabled for one scan cycle period Inputs must stay enabled for one scan cycle period

Internal File Structure Program File Program File Data File Data File Function File Function File Specialty File Specialty File

Program File 0 and 1, processor, passwords, I/O 0 and 1, processor, passwords, I/O 2 ladder program 2 ladder program 3 to 255 subroutines 3 to 255 subroutines

Data File 0 O outputoutput data bits to be copied to I/O 0 O outputoutput data bits to be copied to I/O 1 I inputinput data bits from I/O 1 I inputinput data bits from I/O 2 S statusprocessor status bits 2 S statusprocessor status bits 3 B bit256 words with 16 bits each 4096 individual bits 3 B bit256 words with 16 bits each 4096 individual bits 4 T timer256 words 84 timer instructions 4 T timer256 words 84 timer instructions 5 C counter256 words 84 counter instructions 5 C counter256 words 84 counter instructions 6 R control256 words 84 instructions 6 R control256 words 84 instructions 7 N integer256 words for storage 7 N integer256 words for storage 8 F Floating Point 8 F Floating Point 9 reservedNetwork communications 9 reservedNetwork communications extra storage for any type. However once you start it on one type it is set extra storage for any type. However once you start it on one type it is set.

Extra Data File Types ST String ST String L Long Word L Long Word MG Message MG Message PD PID PD PID PLS Programmable Limit Switch PLS Programmable Limit Switch

Function File Types

Specialty File Types

Addressing Modes Element AddressN7:15 Element AddressN7:15 –used to access a word at a time (integer or control) Word AddressT4:5.PRE Word AddressT4:5.PRE –used to access a word at a time (timer, counter, or control) Bit AddressB3:01.11 or B3/27 Bit AddressB3:01.11 or B3/27 –used to access a bit at a time

Addressing Details

Addressing Examples

Addressing Modes I:7/8 I:7/8 O:5 O:5 S:1/15 S:1/15 B3:252/0 B3:252/0 R6:2/9 R6:2/9 N7:2 N7:2 T4:0.ACC T4:0.ACC C5:244.PRE C5:244.PRE

Other Addressing Modes I:3.1/3 I:3.1/3 O:5.0/2 O:5.0/2 S:32/3 (32 max) S:32/3 (32 max) B10/4095 (4095 max) B10/4095 (4095 max) R15:2/FD R15:2/FD N255:2/8 (255 max) N255:2/8 (255 max) T40:0/TT T40:0/TT C55:244/OV C55:244/OV

Indirect Addressing Mode N7:[N10:1] N7:[N10:1] N[N50:1]:10 N[N50:1]:10 B3/[B25:0] B3/[B25:0]

PLC wiring PLC output power through E-Stop for Diagnostics and not as input in case of frozen PLC PLC output power through E-Stop for Diagnostics and not as input in case of frozen PLC Keep 24V away from 120V and motors Keep 24V away from 120V and motors Try to keep noise to a minimum Try to keep noise to a minimum