Mitsubishi MELSEC AnS (H) series CPUs

Positioning and Applicable Scope

The Mitsubishi MELSEC AnS (H) CPU User Manual covers A1SHCPU, A2SHCPU, A2SHCPU S1, A1SJHCPU, and is equipped with A1S61PN/A1S62PN wide range power modules. It is a complete guide for the design, installation, wiring, debugging, maintenance, and troubleshooting of AnS series compact PLCs.

Safety precautions (mandatory grading)

DANGER: It is necessary to establish external emergency stop, limit, and interlock safety circuits; Power off operation, prohibit touching terminals with electricity on; The battery is prohibited from charging/heating/short circuiting.

CAUTION: The distance between the control line and the power line is ≥ 100mm; the terminals are tightened according to the specified torque; Prohibition of modification and disassembly; Dispose of waste as industrial waste.

System configuration architecture

scalability

Maximum expansion level: 3 levels

I/O points: A1SH=256, A2SH=512, A2SH-S1=1024 points

Support base: Main base A1S32B/33B/35B/38B; Expansion base A1S52B/55B/58B (S1)

Compatible module

Digital I/O, analog, temperature, high-speed counting, positioning CC‑Link、 Ethernet, computer link module

Peripherals: GPP programmer, A6WU ROM writer, A7PU/A8PUE programming unit

Core Performance Parameters 

Project A1SHCPU A2SHCPU A2SHCPU S1

Instruction processing speed 0.33 μ s 0.25 μ s 0.25 μ s

Program capacity: 8k steps, 14k steps, 30k steps

Maximum I/O points 256 512 1024

Built in RAM 64kB 64kB 192kB

File register R has a maximum of 8192 points and a maximum of 8192 points

Watchdog WDT 10-2000ms 10-2000ms 10-2000ms 10-2000ms

Clock function support

Battery backup A6BAT (5 years) A6BAT (5 years) A6BAT (5 years)

Power module A1S61PN

Input: 100-240VAC wide range

Output: 5VDC/5A

Allow instantaneous power outage: ≤ 20ms

Certification: UL/cUL/CE

CPU core functions

Operation mode: RUN/STOP/PANSE; PAUSE can maintain the output state.

Power down hold (Latch): L/B/T/C/D/W data battery backup, supports Latch Clear clearing.

I/O control: Direct mode/Refresh mode can be switched.

Advanced features

Constant scan: 10-2000ms fixed scan

State Lock (SLT): Save all device states in case of failure

Sampling Tracking (STRA): Timing sampling equipment changes for debugging purposes

Offline switch: Forcefully disconnect output during operation for testing purposes

Error LED priority: can block low priority error lights from turning on

Installation and wiring specifications

Install

Method: DIN rail TH35-7.5 or wall mounted

Spacing: ≥ 30mm on all sides; ≥ 80mm on top (expansion base)

Environment: 0-55 ℃, 10-90% RH, no pollution/corrosion

wiring

Power off operation; FG/LG must protect grounding

Strong and weak current separation ≥ 100mm

Shielded cables are used for analog/communication lines, with a single end grounded

EMC and Low Voltage Directive Compliance

EMC: Compliant with EN50081-2/preEN50082-2

Measures: Control cabinet grounding, shielded cable, magnetic ring, power filter, strong and weak current separation

Low voltage command: compliant with EN61010-1; Use reinforced insulation power supply/IO modules; Installed inside a lockable control cabinet

Maintenance and Inspection

Daily inspection: LED status, terminal fastening, module fixation, environmental dust

Regular inspection (6-12 months): voltage, temperature, battery, grounding, connectors

Battery replacement

Lifespan: 5 years

Complete the replacement within 5 minutes after power failure to avoid program loss

Fault diagnosis (core fault code)

10: Instruction code error → Program illegal instruction

11: Parameter Error → Parameter Damage/Memory Card Exception

20: RAM error → CPU hardware failure

22: WDT error → scan timeout, dead loop

31: Module comparison error → Module insertion/model mismatch

32: Fuse blown → Output overload/short circuit

40: Control bus error → Special module/base failure

70: Battery error → low voltage/not connected

Key questions and answers

Question 1: What are the core differences between the three operation modes (RUN/STOP/PANSE) of AnS (H) CPU?

answer:

RUN: Execute the program normally and output actions that follow the program.

STOP: Stop the program, all outputs (Y) are closed, and data remains except for the output.

PAUSE: Stop the program but maintain all current output states, used in pause scenarios where output interruption is not allowed.

Question 2: What are the advantages of the A1S61PN power module? Why do we need to verify the terminal voltage when expanding the system?

answer:

Advantages: 100-240VAC global wide voltage input, no switching required, compatible with global power grids; Instantaneous power outage can withstand 20ms, making the system more stable.

The expansion base is powered by the main power supply through an extension line, and there is a voltage drop in the cables; Require the terminal voltage to be ≥ 4.75VDC, otherwise it may cause module misoperation or crash.

Question 3: What is the reason for the WDT watchdog error (code 22/25)? How to quickly solve it?

answer:

Reason: The program scanning time exceeds the WDT set value (default 200ms), which is often caused by dead loops, excessive instructions, long interrupts, and instantaneous power outages.

solve:

Check for END dead loop

Inserting WDT instruction to reset timer in long program

Increase WDT setting value (maximum 2000ms)

Optimize the program and split long scans