It appears that you are now using Modscan (a generic Modbus master app) rather than writing your own driver (calculating your own CRC?)
Before we get into modbus comm details, why do you believe that you can configure the module via Modbus? Maybe you can, but in many systems, the configuration is the domain of the development software. Is there actually a table or map of configuration parameters with Modbus addresses/registers for the AI module? Or are you expecting to do with Modbus what should be done in the development software?
Now to details:
Are you using RS-232, RS-485 or ethernet to communicate?
Exactly, what communications settings have you applied to
- the Schneider comm module (which model is it?)
- Modscan?