If the issue persists, try another Modbus master software, such as ModScan or CAS Modbus Scanner. This will help you determine if the problem is with Modbus Poll itself or something else in your setup.
A common mistake is setting a single, aggressive scan rate for all registers on all devices. If you are polling a slow device faster than it can respond, you will constantly slam into timeouts and see incomplete responses. On a busy 9600 baud network, if one transaction takes 50ms, a 500ms scan rate across many devices creates a queue, leading to data collisions and errors. modbus poll bytes missing error fixed