MITSUBISHI ELECTRIC GOT1000 Modbus Connection

MITSUBISHI ELECTRIC GOT1000 Series Connection Configuration and Troubleshooting Complete Guide

The Mitsubishi GOT1000 series graphic operation terminal, with its powerful communication capabilities, not only supports multiple connection methods with Mitsubishi PLC, but also exchanges data with non Mitsubishi devices, third-party controllers, and various peripheral devices (barcode readers, RFID, printers, etc.) through MODBUS/RTU, MODBUS/TCP, and microcomputer specific protocols. However, in practical engineering, engineers often encounter issues such as mismatched communication parameters, incorrect cable wiring, and improper protocol format selection, leading to monitoring failures or data confusion. This article is based on the GOT1000 series connection manual (microcomputer, MODBUS products, peripheral devices section), and systematically outlines the entire process from hardware wiring, communication interface configuration to message format selection and fault code troubleshooting. Whether you are connecting a GOT to a MODBUS device for the first time or debugging an unstable RS-485 link, this article will provide operational guidance that can be directly used on site.

GOT1000 series communication interface and preparatory settings

2.1 Communication interface types and physical connections

The GOT1000 series provides multiple physical interfaces:

RS-232: 9-pin D-sub (male or female), with a maximum transmission distance of 15 meters, suitable for point-to-point connections.

RS-422/485: 9-pin D-sub or 14 pin/20 pin dedicated connector (depending on model), maximum transmission distance of 1200 meters (RS-422/485), supports multi-point connection (up to 31 slaves).

Ethernet: RJ45, 10/100Mbps, using direct or crossover Ethernet cables, can connect multiple devices through a hub.

Important wiring specifications:

The length of the RS-232 cable should not exceed 15 meters (as explicitly warned in the manual). Excessive length can lead to signal attenuation and errors.

RS-422/485 must use twisted pair shielded cables and correctly connect terminal resistors. The GOT side usually sets the terminal resistance (110 Ω or 330 Ω) through a dip switch or internal jumper. The terminal device must be in the "termination" position, and the intermediate device must be "disabled".

When connecting to Ethernet, the IP address must not end in 0 or 255 (for example, 192.168.0.0 or 192.168.0.255 are reserved by the system), and when multiple GOTs are connected to the same network, the use of the IP address 192.168.0.18 is prohibited, otherwise it will cause address conflicts and communication abnormalities.

2.2 Communication driver and channel configuration

In GT Designer 3 software, the following two key settings need to be made:

2.2.1 Controller Setting

Select menu [Common] → [Controller Setting].

Select the channel number to be used (CH1-CH4 for connecting controllers, CH8 for barcode readers/RFID/fingerprint authentication and other peripherals that require GOT power supply).

Settings: Manufacturer, Controller Type, I/F, Driver.

For MODBUS/RTU devices: Manufacturer=MODBUS, Controller Type=MODBUS, Driver=MODBUS/RTU.

For microcomputers (custom hosts): Manufacturer=Others, Controller Type=Computer, Driver=Computer (serial) or Ethernet (MICROCOMPUTER).

Click on 'Detail setting' to enter the detailed communication parameter configuration.

2.2.2 I/F Communication Setting

In [Common] → [I/F Communication Setting], assign a channel number (CH No.) to each physical interface (standard I/F-1, I/F-2, etc.).

Channel number 0 indicates not in use; Channel numbers 1-4 are used for communication with the controller; Channel number 8 is specifically designed for peripherals that require GOT to provide 5V/24V power (barcode readers, RFID, etc.).

Important: The same channel number cannot be used for multiple functions simultaneously. For example, if CH8 is already used for fingerprint authentication, it cannot be connected to a barcode reader at the same time.

Microcomputer connection (serial and Ethernet)

The microcomputer (or "host") connection function allows external PCs, microcontrollers, or PLCs to read and write data through the internal virtual device area (D, R, L, M, SD, SM, etc.) of GOT, and supports interrupt output.

3.1 Serial Connection (RS-232/RS-422)

System configuration:

Point to point connection: The GOT is directly connected to the host via RS-232 or RS-422 cable.

Multi point connection: Up to 4 GOTs can be cascaded to one host via RS-232/RS-422 (using dedicated connection cables and connectors).

Message format: GOT supports 15 different formats, including formats compatible with old models GOT-A900/F900, A-series 1C frames, QnA compatible 3C/4C frames, and Digital Electronics Corporation's memory linking method. Common formats include:

Format 1/2 (GOT-A900 series microcomputer connection): Simple ASCII format, no station number.

Format 7-10 (QnA compatible with 3C/4C frames): Supports multiple station numbers and sub station numbers, suitable for complex networks.

Format 14/15 (GOT-F900 series microcomputer connection): Supports batch read/write and fill commands.