I have an rs-485 modbus sensor on a custom RTD board. I have tried to use the libmodbus library (C library to communicate over modbus) to communicate with the sensor hooked up to the board. however it is not working. I see on a scope that the messages are getting transmitted over the line, but I am not sure if I have the correct register as well as slave ID. so thus I am not sure if it is my code or the sensor that is not working. Is there any command line interface program for linux that I can use to see if my sensor is working to help rule out the sensor as the problem?