Sorry to answer a question with another question, but could you give me a sketch of what’s going on in the above setup. We think you are trying to poll to RS485 subnet devices from other manufacturers and using our T3-BB or similar as a general purpose IP to RS485 gateway.
If the assumption is correct then possibly the packets you are sending are not fully supported by our routing functions, our devices support routing for some modbus functions but not all of them. We mainly support the Modbus commands such as read & write registers used by Temco products, that is Modbus functions 03, 06, and 16.
I’m not sure this will help your application but you can do some reading and writing to third party devices with a program running in the T3 controller. See the section titled ‘Network programming’ in the link below for more info on how to do this: