Modbus raw data COM capture file example?
There is no need to compare to someone else's data capture.  The Modbus spec is pretty clear about what makes a valid Modbus packet.

Actually there are two specs that apply in your case.  The first is the Modbus application protocol spec.  That tells you what needs to be in a Modbus packet as seen by the applications on the master and the slave.  They refer to this packet as the PDU.  Then you also need to read the Modbus over serial spec.  That explains how PDUs are wrapped for transmission over a serial line.  This adds a address byte at the start and two checksum bytes after the end of the application-level Modbus PDU.

You may want to get software that can generate packets for your device to resepond to, but looking at someone else's data capture isn't going to tell you anything the spec doesn't.