In order for data exchange to occur, the VendorID, Device Type, Product Code, and input/output sizes must match. If there is no match, the connection breaks, and no data is exchanged. Also, the VendorID, Device Type, Product Code, and input/output sizes cannot be read from the device. The verification only identifies a match in these items, it does not read back the values. Disable I/O Polling and download the device, and then read back Vendor ID, Device Type, Product Code, and input/output sizes using DeltaV Diagnostics to troubleshoot communication problems.