OMRON SYSMAC C20K/C28K/C40K/C60K series K-type programmable controllers

Basic Information

Applicable models: C20K, C28K, C40K, C60K

Core application: Small PLC ladder diagram programming, hardware operation, fault handling

Targeting personnel: Electrical engineers, equipment debugging, system designers

Safety and Installation Standards

Mandatory safety requirements

Power off operation is required, and it is forbidden to disassemble or connect the machine with power on

Grounding resistance * * ≤ 100 Ω * * to prevent electric shock and interference

Prohibited for use in high-risk scenarios such as medical, aviation, nuclear safety, etc

Environmental Requirements

Working temperature: 0-55 ℃, no condensation, no corrosive gas

Stay away from strong electromagnetic, static electricity, and direct sunlight

Hardware and indicator lights

Panel indicator lights: POWER, RUN, ERR, ALARM

Expansion rule: Up to 5 units can be mounted, with C40K/C60K counted as 2 units

Total length of cable: ≤ 1.2 meters

Memory area allocation (core)

Regional abbreviation address range function, power failure maintenance

Internal relay IR 0000-1807 I/O mapping, intermediate variable no

Special relay SR 1808-1907 system flag, clock pulse no

Maintaining the critical state storage of relays HR HR000-HR915 is

Data storage DM DM00-DM63 numerical data storage is

Timer/Counter TC TC00-TC47 Timer/Counter Resource Section

Temporary relay TR TR00-TR07 ladder diagram branch temporary storage No

Key SR Logo

1808: Battery low voltage alarm

1809: Scan cycle timeout (>100ms)

1813: Constant ON; 1812/1814: Constant OFF

1900/1901/1902:0.1S/0.2S/1s clock pulse

1903-1907: ER/CY/GR/EQ/LE operation flags

Programming Mode and Operation

Three working modes

Program: programming, clearing memory, syntax checking

MONITOR: monitoring, forcing, modifying parameters

RUN: Normal operation, program modification is prohibited

Programmer operation

Password unlocking, memory clearing, instruction input/insertion/deletion

Program search, syntax check, scan time display

Programming rules

The program must end with * * END (01) * *

The output bit can only be driven by one OUT command, and duplicate coils are prohibited

Implement branches using TR00-TR07 or IL/ILC

Core Instruction System

1. Logical instructions (basic)

LD/LD NOT: Load normally open/normally closed

AND/AND NOT: series connection

OR/OR NOT: Parallel connection

AND LD/OR LD: Block Logic

2. Process instructions

OUT/OUT NOT: Output

DIFU/DIFD: rising edge/falling edge (limited to 48)

KEEP: Latch Relay

IL/ILC: Interlock/Reset

JMP/JME: Jump (numbers 00-08)

3. Timing and Counting

TIM: 0.1s timer (0-99.9s)

TIMH: 0.01s high-speed timer

CNT: Down Counter

CNTR: Reversible Ring Counter

HDM (61): 2kHz high-speed counter (occupying TC47)

RDM (60): Reversible circular counter (occupying TC46)

4. Data processing instructions

MOV/MVN: Transfer/Reverse Transfer

CMP: Comparison (affecting GR/EQ/LE)

ADD/SUB/MUL/DIV: BCD operation

SFT/SFTR: Shift Register

Debugging and troubleshooting

debugging tool

Program syntax check, scan cycle monitoring

Force bit, modify current/set value

Common mistakes

NO END INSTR: Missing END instruction

CIRCUIT ERR: Logical block mismatch

IL-ILC ERR: Interlock mismatch

COIL DUPL: Repetitive output coil

JMP-JME ERR: Jump not paired

Key issues

Question 1: Which of the 6 memory regions of the C-series PLC support power down hold? What are their respective purposes?

Answer: HR (holding relay) and DM (data storage) support power-off holding.

HR is used to save key information such as start stop status, alarm records, and mode selection;

DM is used to store textual data such as parameters, cumulative values, formula data, etc., without loss during power outages.

Question 2: What is the difference between TIM and TIMH instructions? How to choose in the program?

answer:

TIM: Time base of 0.1 seconds, range of 0-99.9s, low accuracy, suitable for conventional delays;

TIMH: Time base of 0.01 seconds, range of 0-99.99 seconds, high accuracy, suitable for fast timing.

Selection rule: TIM must be used for at least 1 second; Requires<1 second high precision * * using TIMH.

Question 3: IL/ILC and JMP/JME are both process controls. What are the core differences and applicable scenarios?

answer:

IL/ILC (Interlock): Reset timer and clear output when conditions are not met, suitable for safe shutdown and emergency stop logic;

JMP/JME (Jump): Keep all outputs/states unchanged when conditions are not met, suitable for energy-saving skipping and function blocking.

Simple note: To cut off the output, use IL; to maintain the output, use JMP.