MITSUBISHI ELECTRIC GOT1000 Modbus Connection

When the function code of the connected MODBUS device is limited or the length of a single frame of data is small, it can be dynamically adjusted through the special registers (GS570~GS576) inside GOT:

GS570.0: Set to 1 to disable function code 0F (write multiple coils); GS570.1: Set to 1 to disable function code 10 (write multiple registers).

GS571~GS576: Set the maximum number of points allowed for each function code separately (for example, the maximum number of reading coils can be set to 1000 instead of 2000).

GS579: Used for selecting shared or independent settings when multiple channels are available (one set of GS590~GS617 per channel).

Important: These GS registers must be set at once through project scripts during GOT startup, and any changes made during runtime may cause communication errors.

MODBUS/TCP connection

GOT, as a MODBUS/TCP client, can connect to multiple server devices (such as Schneider Modicon, Yokogawa STARDOM, etc.).

5.1 Key points of setting

In the controller settings, select "MODBUS/TCP, Gateway" for the Driver.

Set the network number (1-239), PLC number (station number, 1-247), and IP address of GOT.

In the "Ethernet Settings" tab, add the IP address and port number (usually 502) of the target MODBUS/TCP server, as well as the network and station numbers of the server.

5.2 IP address restrictions when connecting multiple GOTs

When there is only one GOT in the network, other controllers are prohibited from using the IP address 192.168.0.18.

When there are multiple GOTs, no device (including GOTs) should use 192.168.0.18, otherwise it will cause address duplication and communication failure.

5.3 Troubleshooting

Possible causes and actions of the phenomenon

Connection failed, GOT shows' Target IP unresponsive '. The server port is not 502 or the firewall is blocking the confirmation server from listening on the port and allowing it in the router

Data read error, register address mapping error check, device address translation (Modbus address starts from 0, GOT device number starts from 1, pay attention to offset)

Periodic timeout: excessive network load using a switch hub; Increase the timeout period (up to 90 seconds); Reduce the number of monitoring points

Key points for connecting peripheral devices (barcode/printer/RFID/external I/O)

6.1 Barcode Reader Connection

Channel number 8 (standard interface) must be used and GOT needs to provide power. If the barcode reader is self powered, it can be connected to channels 5-7.

The termination symbol must be set (such as CR, LF) and consistent with the output of the barcode reader.

Specify the storage device for receiving data (such as D0 offset) through the "Bar Code" peripheral settings.

Common problem: Incomplete scanning data → Check the byte order (Low/High) and padding characters (Space/null) for writing.

6.2 Printer Connection

Supports PictBridge compatible printers (via USB) and serial printers (RS-232).

The serial printer must have the same baud rate, data bits, etc. as the GOT settings. Note: The hard copy function requires data bits of 8 bits.

Problem: The printer sends a "ready" signal too early during initialization, causing errors when GOT starts printing. Before restarting the printer, disconnect the USB cable and wait for complete initialization before connecting again.

6.3 RFID Connection

Supports multiple specialized protocols (such as LSIS, MARS TOHKEN ICU series, etc.), selected through "Format".

The external authentication function must use channel 8. If RFID requires GOT power supply, it can only use channel 8.

Multi reader interlock: Interlocking needs to be implemented in the controller program to prevent simultaneous communication.

6.4 External I/O devices (operation panel)

Use GT15-DIO (positive common input/drain type output) or GT15-DIOR (negative common input/source type output).

Supports 16 point input/16 point output, or 128 point matrix input (through scanning signals).

When wiring, attention should be paid to the direction of the diode (each switch must be connected in series with a diode to prevent crosstalk when inputting the matrix).

System level fault diagnosis method

7.1 Use GOT's built-in communication monitoring function

Enter the Utility menu of GOT ->"Communication Settings" ->"Comm. Monitor" to view the communication status, send/receive frame count, and latest errors of each channel.

For Ethernet connections, you can perform a Ping test through the Windows command prompt or perform a "PING test" in GT Designer 3.

7.2 Interpretation of Error Codes in Special Data Register (SD2)

When a communication error occurs, GOT will store the error code in the internal SD2 register. Common values:

Error code (decimal) meaning handling

1 (101) Parity Error Check Check Check Bit Setting and Cable Quality

2 (102) frame error check stop bit and data bit

3 (103) Exceeding limit error reduces baud rate or checks CPU load

4 (104) Message error check message format and terminator

5 Command Error Confirmation: Is the function code used supported

105 timeout error check for slave power, cable, and station number