Mitsubishi MELSEC AnS (H) series CPUs

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