Complete Guide to Field Application and Troubleshooting of Mitsubishi GT15-RS2/4 Serial Communication Unit

Complete Guide to Field Application and Troubleshooting of Mitsubishi GT15-RS2/4 Serial Communication Unit

In automated production lines, serial communication between human-machine interface (HMI) and on-site devices such as PLC, frequency converter, and instruments is the foundation of data exchange. The Mitsubishi Electric GOT2000/GOT1000 series graphic operation terminal, with its rich expansion capabilities, can flexibly connect multiple interfaces such as RS-232, RS-422, RS-485 through a dedicated serial communication unit. Among them, the GT15-RS2-9P, GT15-RS4-9S, and GT15-RS4-TE units cover point-to-point and multi-point communication scenarios, and are widely used in the renovation of old production lines, remote equipment monitoring, and multi station data acquisition.

However, serial communication is limited by factors such as wiring quality, terminal resistance matching, and shielding grounding, and on-site engineers often encounter tricky problems such as "unstable communication", "occasional disconnections", and "inability to establish connections". This article combines Mitsubishi's official technical information and years of on-site maintenance experience to systematically sort out the technical specifications, installation steps, wiring specifications, and quick troubleshooting process of these three serial communication units, providing a practical "pocket guide" for automation maintenance personnel.

Chapter 1 Model Overview and Selection Points

Mitsubishi provides three types of serial communication expansion units for the GOT2000/GOT1000 series, corresponding to different electrical interfaces and application scenarios.

Model Interface Type Connector Form Maximum Transmission Distance Typical Applications

GT15-RS2-9P RS-232 D-sub 9-pin (male) 15 meter close range connection to Mitsubishi PLC, barcode scanner, printer

GT15-RS4-9S RS-422/485 D-sub 9-pin (female) 1200 meter multi station RS-485 network, connected to frequency converters and instruments

GT15-RS4-TE RS-422/485 terminal block (pluggable) 1200 meters for industrial environments requiring high reliability wiring, convenient for shielded cable handling

Key points of selection decision:

If the communication distance is ≤ 15 meters and only a single device needs to be connected, choose GT15-RS2-9P (RS-232). Note that this unit cannot be used for multi station networks.

If long-distance (up to 1200 meters) or multi station (1: N) communication is required, RS-422/485 type must be selected. Among them, GT15-RS4-9S is convenient for using standard D-sub cables, while GT15-RS4-TE is suitable for on-site self-made cables that require good shielding grounding.

Special restriction: GT15-RS4-TE does not have RS/CS hardware flow control signals, so it cannot be directly connected to specific PLCs (some older models) that rely on this signal. Please refer to the Mitsubishi Connection Manual before selecting.

Chapter 2 Detailed Explanation of Technical Specifications

2.1 Performance Parameters

All three units share the following communication parameters:

Transmission speed: 115200/57600/38400/19200/9600/4800 bps (configurable)

Synchronization method: Asynchronous (start stop)

Error detection: parity check, sum check

Internal current consumption (5VDC):

GT15-RS2-9P：0.29A

GT15-RS4-9S：0.33A

GT15-RS4-TE：0.30A

Weight: Approximately 0.09kg

Attention: When using a serial communication unit, the GOT needs to install a standard monitoring OS and communication driver, with version GT Modeler 2 Version 2.15R or higher. The old version firmware cannot recognize the unit, which can result in an error of 'expansion unit not detected'.

2.2 Environment and General Specifications

The general specifications of the serial communication unit are consistent with the installed GOT host. For example, when installed on the GT15 series, the working temperature range is 0-55 ℃, the storage temperature is -20~60 ℃, and the humidity is 10-90% RH without condensation. The impact resistance follows the IP rating of the GOT host (usually IP67F or IP20F). In sites with severe dust, oil mist, or vibration, additional protective covers are required.

2.3 Terminal block specifications (GT15-RS4-TE only)

GT15-RS4-TE adopts a pluggable terminal block for easy cable maintenance:

Screw torque: 0.20~0.25 N · m (terminal block fixing screw); 0.5~0.6 N · m (wire clamping screw)

Applicable wire: 0.08~1.5 mm ²

Recommended tool: Screwdriver that meets DIN 5264 standard, with chrome plated tip

Shielding layer treatment: Comes with plate type crimping terminals for connecting shielding braided mesh

Chapter 3 Installation and Expansion Structure

3.1 Unit installation steps (taking GT1575 as an example)

The serial communication unit is installed on the expansion interface on the back of the GOT. The installation process does not require special tools, but the following sequence must be strictly followed:

Power off: Turn off GOT and all external power sources of the system (completely cut off all phases).

Remove the cover plate: Remove the expansion unit cover on the back of the GOT (one or two, depending on the installation position).