IDEC MicroSmart FC6A Replacement Guide

IDEC MicroSmart FC6A Replacement Guide

Introduction: When old PLCs are discontinued - the upgrade value of MicroSmart FC6A

In the fields of small and medium-sized automation equipment, water treatment systems, packaging machinery, and mobile vehicle control (such as engineering machinery and agricultural equipment), once the PLC controller is shut down (EOL), equipment maintenance personnel often find themselves in a dilemma: either look for expensive and non warranty second-hand dismantling parts, or bear the high cost of retrofitting. IDEC's MicroSmart FC6A series, as a powerful integrated CPU module, is an ideal choice to replace outdated MicroSmart series (such as FC5A, FC4A) and other brands' discontinued PLCs with advanced features such as built-in Ethernet, SD card storage, dual serial ports (RS232/RS485 optional), Modbus TCP/RTU, and SAE J1939 (CAN bus).

This article is based on the technical specifications of FC6A series CPU modules, and provides a detailed analysis of the selection comparison, I/O specifications, communication capabilities, and complete process of replacing old PLCs for each model from an engineering perspective. It also provides common troubleshooting methods. Whether you are planning to upgrade equipment or looking for alternative solutions for discontinued spare parts, this article can provide directly usable references.

FC6A Series Overview: Integrated High Performance PLC

The FC6A (MicroSmart 6th generation) CPU module adopts an integrated design, integrating the power supply, CPU, I/O points, and communication interfaces into the same unit. Its core features include:

Built in Ethernet ports: 10BASE-T/100BASE-TX, supporting Modbus TCP (server/client), user communication, SNTP, PING, etc.

Built in SD memory card slot: used for program backup, data logging, recipe management, etc.

Dual serial ports (RS232 C/RS485 optional for users): Supports Modbus RTU master/slave.

USB port (Mini-B, USB 2.0 full speed): used for programming and maintenance communication, not isolated.

Maximum I/O expansion capability: 520 digital I/O and 126 analog I/O can be achieved through local expansion modules.

Built in high-speed input: Some input ports support a response time of 5 µ s, suitable for high-speed counting and pulse capture.

Built in PWM/pulse output: The transistor output type supports pulse output up to 65 kHz.

SAE J1939 model: designed specifically for vehicle and engine control applications, integrated with CAN bus (250 kbits/s), supporting J1939-11/15/21/71/73/75/81 protocol.

FC6A offers three body specifications of 16, 24, and 40 points, each with relay output, transistor source type, and transistor drain type versions. The power supply voltage can be selected from 100-240V AC, 24V DC, or 12V DC, and some models also offer SAE J1939 version.

Comparison Table for Selection of Standard CPU Modules

3.1 16 o'clock CPU module (8-in/7-out)

Model Power Supply Voltage Input Voltage Output Type Maximum Digital I/O Maximum Analog I/O

FC6A-C16R1AE 100-240V AC - Relay 400 100

FC6A-C16R1CE 24V DC 24V DC Relay 400 100

FC6A-C16P1CE 24V DC 24V DC transistor source type 400 100

FC6A-C16K1CE 24V DC 24V DC transistor leakage type 400 100

Input point: 9 o'clock (including high-speed input, compatible with 24V DC sink source)

Output point: 7 points (relay or transistor)

3.2 24 o'clock CPU module (14 inputs/10 outputs)

Model Power Supply Voltage Input Voltage Output Type Maximum Digital I/O Maximum Analog I/O

FC6A-C24R1AE 100-240V AC - Relay 504 124

FC6A-C24R1CE 24V DC 24V DC Relay 504 124

FC6A-C24P1CE 24V DC 24V DC transistor source type 504 124

FC6A-C24K1CE 24V DC 24V DC transistor leakage type 504 124

Input point: 14 points (compatible with 24V DC sink source)

Output point: 10 o'clock

3.3 40 point CPU module (24 in/16 out)

Model Power Supply Voltage Input Voltage Output Type Maximum Digital I/O Maximum Analog I/O

FC6A-C40R1AE 100-240V AC - Relay 520 126

FC6A-C40R1CE 24V DC 24V DC Relay 520 126

FC6A-C40P1CE 24V DC 24V DC transistor source type 520 126

FC6A-C40K1CE 24V DC 24V DC transistor leakage type 520 126

FC6A-C40R1DE -12V DC Relay -

FC6A-C40P1DE 12V DC 12V DC transistor source type 40 6

FC6A-C40K1DE 12V DC 12V DC transistor drain type 40 6

Input point: 24 points (compatible with 24V DC or 12V DC sink source)

Output point: 16:00

The 12V version has a lower maximum I/O expansion capability (digital 40/analog 6) and is suitable for in car or other low-voltage applications.

SAE J1939 CPU module (CAN bus)

Suitable for applications such as construction vehicles, agricultural machinery, and generator sets that require communication with the engine ECU. All J1939 models are 40 point body (24 in/16 out), supporting J1939-11 (shielded twisted pair) and J1939-15 (unshielded twisted pair) physical layers, with a speed of 250 kbits/s. Up to 100 messages can be sent and 200 can be received, supporting address declaration, network management, and more.

Model Power Supply Voltage Input Voltage Output Type Maximum Digital I/O Maximum Analog I/O

FC6A-C40R1AEJ 100-240V AC - Relay 250 126

FC6A-C40R1CEJ 24V DC 24V DC Relay 250 126

FC6A-C40P1CEJ 24V DC 24V DC transistor source type 250 126

FC6A-C40K1CEJ 24V DC 24V DC transistor drain type 250 126

FC6A-C40R1DEJ -12V DC Relay -

FC6A-C40P1DEJ 12V DC 12V DC transistor source type 40 6

FC6A-C40K1DEJ 12V DC 12V DC transistor drain type 40 6

Note: The maximum digital I/O capacity of J1939 model (250 points) is lower than that of non J1939 version (520 points), as some system resources are used for CAN communication.

Detailed explanation of input specifications (key parameters)

All inputs of FC6A CPUs are sink source compatible and can be connected to NPN or PNP sensors without damage when reversed.

5.1 24V DC input (applicable to 24V power supply models)

Parameters: High speed input port, medium/constant speed input port

Rated input current 5 mA 7 mA

Input impedance 4.9 k Ω 3.4 k Ω

Minimum ON voltage 14.4V 14.4V

Maximum OFF voltage 5V 5V

Conduction delay 5 µ s+filter 35 µ s+filter

Turn off delay 5 µ s+filter 100 µ s+filter (constant speed)

Filter: Can be configured through software (0-32 ms) to eliminate contact jitter.

High speed input: can be used for high-speed counting or pulse capture at 50 kHz.

5.2 12V DC input (applicable to 12V models)

Parameters: High speed input, medium speed/constant speed

Rated input current 5 mA 6 mA

Input impedance 1.8 k Ω 2.0 k Ω

The on/off delay is the same as the 24V version. The analog I/O expansion capability of the 12V model is limited (up to 6 analog channels), but digital I/O can still be expanded to 40 points.

Detailed explanation of output specifications

6.1 Relay output (R1A/R1C/R1D models)

Parameter specifications

Maximum load per point 2A (resistive), 240V AC/30V DC

Maximum total current per common terminal 7A (COM1/COM2/COM4), 6A (COM3 depending on model)

Minimum load 1 mA/5V DC (reference value)

Electrical lifespan 100000 times (rated load, 1800 times/hour)

Mechanical lifespan of 20000000 cycles (no load)

Initial contact resistance ≤ 30 m Ω

Insulation withstand voltage 1500V AC (output to ground, output to output)

Engineering Tip: Relay output is suitable for AC loads or low-frequency switches, but attention should be paid to surge suppression (RC absorption or varistor) for inductive loads. The typical shutdown delay of the constant speed output port (non high speed) is 300 µ s, which is not suitable for high-frequency PWM output.

6.2 Transistor Output (P1C/K1C/P1D/K1D Models)

Parameters 24V model 12V model

Rated load voltage 24V DC 12V DC

Voltage tolerance 19.2~28.8V 10.2~18.0V

Maximum current per point 0.5A 0.5A

Maximum current per common terminal 3.5A (8 points/common terminal) 4A (specific model)

ON voltage drop ≤ 1V ≤ 1V

Leakage current ≤ 0.1 mA ≤ 0.1 mA

Overcurrent protection source type: current limiting resistor detection (4 points share one detection signal)

Leakage type: No same left

Shutdown delay (constant speed) 300 µ s 300 µ s

Turn off delay (high-speed) 5 µ s 5 µ s

High speed output port (specific point only): configurable for 65 kHz PWM or pulse train output (PTO) for servo step control.

Overcurrent protection mechanism: When the total current of a group of 4 output points exceeds the standard, the CPU will detect it through an interrupt and turn off the group's output within about 1 second to avoid damage. But the leakage type output does not have this protection and requires an external fuse.

Communication and network capabilities

The powerful communication capability of FC6A is its core advantage in replacing old PLCs.

7.1 Ethernet port (standard for all models)

Physical layer: 10BASE-T/100BASE-TX, RJ45, CAT. 5 or STP, maximum length of 100m, pulse transformer isolation.

Protocol support:

Modbus TCP (Server/Client)

User communication (no protocol, via socket API)

Maintain communication server (for programming software WindLDR)

PING (Network Diagnosis)

SNTP (Simple Network Time Protocol)

7.2 Serial port (RS232C/RS485 configurable)

Located on the same 8-pin RJ45 port, select RS232C or RS485 (2-wire/4-wire) through software. Support:

Modbus RTU master/slave

User communication (no protocol)

Directly connected to IDEC human-machine interface

7.3 USB Port (Mini-B)

USB 2.0 at full speed, not isolated (shared with internal circuitry), used for programming, monitoring, and data uploading and downloading. When used on industrial sites, it is advisable to avoid environments with long distances or severe electromagnetic interference.

7.4 SD memory card slot

Supports SD/SDHC cards (up to 32 GB) for:

Program backup and automatic loading

Data log (CSV format)

Formula parameter storage

Firmware update

7.5 SAE J1939 (J1939 model only)

Physical layer: J1939-11 (shielded twisted pair) or J1939-15 (unshielded twisted pair), with a speed of 250 kbit/s.

Data link layer: J1939-21 (supports multi packet transmission).

Application layer: J1939-71 (vehicle), J1939-75 (generator set and industrial), J1939-73 (diagnosis).

Network management: J1939-81, supports address declaration (static/dynamic).

Maximum number of messages sent: 100, receive 200.

Message length: 1-252 bytes per message.

Transmission method: event triggered or cycle triggered (cycle can be set to 10~655350 ms).

Built in PGN (parameter group number): 0x00EA00 (request), 0x00EB00 (confirm), 0x00EC00 (TPDT), 0x00ED00 (TPCM), 0x00EE00 (address declaration).

Typical application: Connect diesel engine ECU to read speed, water temperature, oil pressure, fault codes, etc., or control engine start stop and throttle.

The complete process of replacing the discontinued PLC

8.1 Identify key parameters of the original PLC

Before replacing discontinued PLCs (such as IDEC FC5A/FC4A, Mitsubishi FX series, Omron CP1 series, etc.), it is necessary to record:

I/O points and types: digital input/output points, analog input/output points.

Input voltage: AC 110V, 24V DC, 12V DC or other.

Output types: relay, transistor (NPN/PNP), bidirectional thyristor.

Power supply voltage: AC 220V, 24V DC, 12V DC.

Communication requirements: Do you need to communicate with touch screens, frequency converters, and upper computers (Modbus RTU/TCP, CAN, etc.).

Special functions: high-speed counter, pulse output, shaft control.

8.2 Select the closest model based on the FC6A selection table

Example:

Reasons for recommending FC6A model based on original PLC specifications

24V DC power supply, 8-in/6-out relay FC6A-C16R1CE 16 point body, relay output

24V DC power supply, 14 input/10 output transistor source type FC6A-C24P1CE point and output type matching

220V AC power supply, 24 in/16 out relay FC6A-C40R1AE 40 point body built-in 24 in/16 out

Engineering vehicles require reading engine CAN data FC6A-C40R1CEJ with J1939 interface

Mobile devices powered by 12V batteries FC6A-C40P1DE or K1DE 12V transistor versions

If the number of I/O points of the original PLC exceeds the maximum number of points (40 points) of the FC6A body, an expansion module is required. FC6A supports local expansion of FC6A series (digital/analog/temperature, etc.), with a maximum total of 520 digital+126 analog points.

8.3 Hardware Installation and Wiring

Physical installation: FC6A is installed using standard 35mm DIN rails, with widths depending on the number of points: 16 point and 24 point units are approximately 87mm wide, and 40 point units are approximately 155mm wide. If the original PLC installation holes are different, it is necessary to replace the guide rail or process the base plate.

Power wiring: AC models are directly connected to 100-240V; DC models are connected to the corresponding DC voltage (pay attention to positive and negative polarity). The 12V model cannot be connected to 24V.

Input wiring: The input of FC6A is sink source compatible, which can be wired as NPN (common positive) or PNP (common negative) without changing the sensor type. It is recommended to use shielded cables with a length not exceeding 3 meters (to meet electromagnetic immunity).

Output wiring: Relay output can directly replace the original relay output; The transistor output needs to confirm that the load voltage is consistent with the original system (24V or 12V). If the original output is AC 110/220V, the relay output model must be used.

Communication wiring: Ethernet uses CAT. 5e and above Ethernet cables; Use dedicated programming cables or self-made RJ45 to DB9 cables for serial ports (see manual for pin definitions); CAN (J1939) uses shielded twisted pair cables with a terminal resistance of 120 Ω.

8.4 Program Conversion

Use IDEC's WindLDR programming software (supporting FC6A) or Automation Organizer. If the original program is FC5A/FC4A PRJ files can usually be directly imported and CPU model settings can be changed, but it is necessary to check:

I/O address mapping: The input and output addresses of FC6A range from I0~I27 (24 point model) or I0~I39 (40 point model), which may be different from the old model. Batch reallocation is required.

Special registers: Some system flag bits (such as normally ON, normally OFF, scan pulses) may have address changes.

High speed counter configuration: The high-speed counter parameters of FC6A are set through software, which is different from the hardware mode switch of the old model.

Communication instructions: The syntax of Modbus instructions (such as MODR, MODW) may be compatible, but testing is recommended.

If the original PLC is from another brand (Siemens, Mitsubishi, etc.), the ladder diagram needs to be rewritten according to the logic of the new program. The rich instruction set of FC6A (arithmetic, comparison, shift, PID, floating-point, etc.) can be utilized to achieve the same functionality.

8.5 Testing and Verification

Before powering on: Use a multimeter to confirm that the power supply voltage is correct and that there is no short circuit at the output terminal.

Download the program: Connect the PC via USB or Ethernet and download the rear CPU for RUN.

Mandatory testing: Use software to force the output point ON/OFF and check the action of the on-site actuator.

Input check: manually trigger on-site sensors, observe input indicator lights or software monitoring.

Communication testing: Verify data exchange with touch screen, frequency converter, and SCADA one by one.

Run with load: Run continuously for at least 8 hours, check CPU temperature, power stability, and functional integrity.

Common troubleshooting guide

Possible causes and solutions for the fault phenomenon

CPU power LED not lit, power supply missing or reversed polarity; Measure the voltage of the power terminal (AC or DC) when the power module is damaged, and check the fuse

Error LED flashing or constantly on program error; Hardware malfunction; Watchdog timeout connection to WindLDR, reading error code (E * * *); Clear watchdog timer setting too small

The input point is unresponsive and the sensor is faulty; Loose wiring; Measure the voltage of the input terminal to COM using a multimeter when the input common terminal is not connected; Check the power supply of the sensor; Refer to input specifications to confirm voltage threshold

Output point does not operate, load disconnected; Output overload protection triggered; Relay lifespan to check load and fuse; For transistor source type, after resetting overload, wait for 1 second for automatic recovery; Replace the relay module

Ethernet cannot communicate due to IP address conflicts; Wrong network cable type (direct/cross); Switch failure is tested using a crossover cable connected directly to a PC; Modify IP through WindLDR; check firewall

Modbus communication failure baud rate/parity mismatch; The address of the slave station is incorrect; Check communication parameters for wiring errors; Use serial debugging tools to listen for data; Check the RS485 terminal resistance

J1939 no data CAN bus physical fault; Node does not declare address; PGN is not configured to measure the voltage between CAN_S and CAN_L (≈ 2.5V each); Check the terminal resistance (120 Ω); Use software to monitor and receive messages

SD card cannot recognize card not formatted (FAT32); If the capacity exceeds 32 GB, format it as FAT32 on a PC; Use a 32GB or smaller capacity card

After the program is lost, the CPU enters STOP and the battery voltage is low (FC6A internal flash does not require a battery, but RTC requires a battery). Download the program again; Check RTC battery (optional)

Maintenance and spare parts recommendations

The FC6A series uses flash memory to store user programs, without the need for battery retention (except for real-time clocks). Therefore, the daily maintenance workload is relatively low. Suggestion:

Check once a year: clean the dust inside the cabinet, tighten the wiring terminals, and inspect the cooling fan (if any).

Regular backup: Backup programs and parameters through WindLDR or SD card.

Spare parts recommendation: Reserve at least one CPU module of the same model, as well as commonly used I/O expansion modules and power modules.

Firmware upgrade: Follow the IDEC official website as the new firmware may fix known issues or add features.