The catalogs for IOM0080, IOM0080T, IOM01200 and IOM12682 specify Modbus RTU with defaults of 9600 baud, 8 data bits, 1 stop bit, no parity and device address 1. Check modules individually before connecting several on one bus to avoid duplicate addresses.
These manuals identify 40001 as the address register and 40002 as the baud-rate register. They require a power restart for parameter changes to take effect and all four address switches OFF when setting the address through software. This applies to the listed models and manual versions, not every I/O product.