Anybus X-gateway AB9008-B -- Changing the Starting Holding Register


I’ve got a customer that wants to install upwards of 50 of the AB9008 X-gateway. I’ve been working on getting the first unit working and have hit a snag with the starting Holding Register. The customer needs the MODBUS map to start at register 40001, but the X-gateway seems to want to start at 34448. Is there a way that this can be changed?


You can disregard the Registers under “Parameter Data”. The gateway will map the transactions starting at the first available register, for example, 40001 if you are not using a Status Word or Live List.

Check the Mapping Overview for a summary:

Hi Kyle,

Thanks for the response. However, I’m confused how I could just “disregard” the Registers as you described. When I use MODBUS polling software, I cannot see any data being exchanged at the 40001-40041 Register. Please see confirmation of this in the picture below:

When I poll looking at the 34448 Register that is defined in the “Parameter Data” section, I am clearly able to see that data is being exchanged as expected. See below:

See the “Mapping Overview” of my setup below:

I’m sorry, I think I gave you the wrong register to start:


If you are reading Input registers it would be 30001, but for Holding registers, it’s 0x100 or 40256. There’s not a way to change it to 40001.