MITSUBISHI ELECTRIC MELSEC iQ-R/Q/L Complete Guide

Complete analysis of communication network and interface module

Mitsubishi Electric provides an integrated network solution from the sensor layer to the management layer:

Network type, speed characteristics, typical modules

CC Link IE Control 1 Gbps fiber dual ring, redundant control layer RJ71GP21-SX

CC Link IE Field 1 Gbps Ethernet cable, device layer/field layer RJ71GF11-T2

CC Link (Ver.2) 10 Mbps Classic Fieldbus RJ61BT11

Ethernet 100 Mbps standard TCP/IP, supports SLMP RJ71EN71

PROFIBUS DP 12 Mbps third-party device integrated RJ71P891

PROFINET 100 Mbps Siemens Ecosystem RJ71PN92

EtherNet/IP 100 Mbps Rockwell Integrated RJ71EIP91

SLMP seamless communication: Through the SLMP protocol, upper computer software (such as MX Component) or smart devices (such as visual sensors) can directly read and write software components from any station in the network, without worrying about network hierarchy. For example, accessing remote stations in the CC Link IE Field network through Ethernet from an enterprise level switch.

Fault case: CC Link IE Field network frequently disconnects. Use CC Link IE Field diagnostic tool (in GX Works3) to view the received optical power and error frame count of each station. The common reasons are that the bending radius of the cable is too small (required to be>8 times the outer diameter of the cable), the connector is not locked, or a non shielded ordinary network cable is used (Cat5e or above double shielded/STP cable must be used). Replace with dedicated SC-ESEW series Ethernet cables.

Upgrade and replacement strategy from A/AnS series to new platform

Many factories are still using the MELSEC A series (such as A1S, A2U), facing spare parts shutdowns and insufficient performance. Mitsubishi provides a complete upgrade path:

6.1 Hardware adaptation

Substrate adapter: Install the Q series substrate onto the fixing hole of the original A series substrate (using QA1S6?)? Specific names: ERNT terminal block adapters and base rack adapters.

Terminal block conversion: Use ERNT series adapters to directly transfer the wiring terminals of AnS series modules to Q series modules without rewiring.

Module compatibility: Some AnS series I/O modules can be used on Q series substrates (via QA1S51B expansion substrate).

6.2 Software Conversion

Upgrade tool: Convert A-series programs (using GX Developer) to iQ-R series programs (using the "Import A-series Projects" feature of GX Works3). After conversion, it is necessary to check special software components (such as M9000 series) and instruction differences (such as changing the original SPD instruction to a high-speed counter module).

Tag replacement: The A series uses absolute addresses, while iQ-R supports structured tags. Suggest gradually replacing important data points with labels after conversion to improve readability.

6.3 Recommended Replacement Comparison Table

Recommended Replacement Models for Old Models: Precautions

A1SCPU L02CPU program capacity increased from 3k steps to 20k steps, and I/O points increased from 256 to 1024

A2UCPU Q03UDV Ethernet built-in, program increased from 30k steps to 30k steps (actually the same but with improved performance)

A3UCPU Q06UDV speed increased from 0.2 μ s/step to 1.9 ns/step

AnS redundancy Q12PRHCPU or iQ-R redundancy requires replacement of substrate and power supply, and addition of fiber optic synchronization module

Best Practices in Programming and Engineering Software

7.1 GX Works3 and iQ Works

GX Works3 is the standard programming environment for the iQ-R series, supporting five languages of IEC 61131-3 (LD, IL, FBD, ST, SFC). Special features:

System tag: Share variables between PLC, motion CPU, and GOT (HMI), and synchronize all devices with just one modification.

Simulation function: Offline simulation of PLC programs, including motion control and network communication.

Batch reading: Upload programs, parameters, and comments from multiple PLCs simultaneously, significantly reducing maintenance time.

7.2 Practical Techniques for Structured Text (ST)

For complex algorithms such as temperature PID self-tuning and flow accumulation calculation, using ST is more efficient than using ladder diagrams. Common ST error: Forgetting to set initial values for local variables, resulting in random data during the first scan. Solution: Initialize all variables with IF FirstCycle THEN at the beginning of the program.

7.3 Remote Maintenance and Diagnosis

GX Works3 remote connection: Through Ethernet penetration function, access the on-site PLC from the office PC via VPN.

Web server module (QJ71WS96): Built in web page, can remotely monitor software component values, modify parameters, and view fault logs.

MES interface module (RD81MES96): directly writes production data into SQL databases (Oracle, SQL Server) to achieve data collection without intermediate PCs.

Quick Reference Table for Common Fault Codes (Based on Field Experience)

Possible causes and solutions for faulty modules/systems

ERR light flashing, iQ-R CPU program memory verification error, re download program; Replace battery (Q6BAT)

Sudden shutdown during operation, Q series redundant tracking cable looseness inspection, QC10TR two end plugs; Replace the cable