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 (hex 04 = slot 4, hex 05 = 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

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