ModMaster Manual v3.14 - 5.1.2. Custom commands
The Custom Command page enables you to define and send non-standard Modbus commands.
The following values must be entered:
Slave ID. See Slave ID in the previous section.
Function. Enter the Modbus function code for the command, in decimal.
Count. Enter the number of bytes of data that you want to send.
Send data. Enter the data bytes that you want to send, in hex.
If you want to enter all the data bytes as a group using copy-paste or drag-and-drop (e.g. from the trace output), you should paste/drop on to a grey cell in the table. The Count value will be set automatically if you enter the data this way.
The header/CRC/LRC will be added to the command as appropriate to the packet type (TCP/RTU/ASCII) that you have configured.
When you send the data to the slave, any data received in response from the slave will be displayed in the Received Data table. This data does not include the slave ID, function code and header/CRC/LRC bytes.