Is it possible to have a READ_REG or WRITE_REG function block bridge Ethernet to Modbus through a TSXETG100?
Yes. A READ_REG or WRITE_REG block can reach a serial Modbus device through a TSXETG100 gateway, using the block's ADDRFLD parameter to carry both the gateway's address and the target device's ID.
How it works:
ADDRFLD is a 5-word array (WordArr5). Its 5 words are split across two roles:
| Word(s) | Contents |
| Word 1 (high byte) | Physical slot of the Ethernet module in the local rack |
| Word 1 (low byte) | The target device's Local ID, as configured in the TSXETG100's Device List |
| Words 2–5 | TSXETG100's IP address, one octet per word |
Example: to reach a device with Local ID 5 through a TSXETG100 at IP 192.168.40.7, with the Ethernet module in slot 4:
- Word 1 =
16#0405(hex04= slot 4, hex05= Local ID 5) - Words 2–5 =
192,168,40,7
Note : The low byte of word 1 is the device's Local ID as set up on the TSXETG100 itself (Setup > Device List, Slave mode) — not necessarily its real serial slave address. The gateway's Device List maps each Local ID to a Remote ID (the device's actual address on the serial line). Check the gateway's Device List to confirm which Local ID has been assigned to the device you're targeting