I have a modbus RTU relay module connect to the main RS485 of the T3 Nano ESP. I try to search on this forum about send command to on/off the relay with programing with T3000 but not clearly understand.
The relay module have address FF (255), T3 address 1, hex command to turn on the relay:
FF 0F 00 00 00 08 01 FF 30 1D
30 1D is the CRC
Command to turn on the relay:
FF 0F 00 00 00 08 01 00 70 5D
70 5D is the CRC
Command to red relay status:
FF 01 00 00 00 08 28 12
I have test and it work with USB-RS485 adapter but I want to control the module with T3000.
I try some code like
What about CRC, is it auto calculated by the T3 Nano? I changed the relay module to address 02 and try your code but it’s not working. My T3 Nano panel ID is one, I connect the RS485 relay module to main port and set it as master.
The 1 byte before the stop bit is the CRC check, which belongs to the Modbus standard protocol.
Register 12 is an example, and you need to confirm which register is the one that controls your third-party device.
And you need to figure out what value is written to turn on the relay of this third-party device.
Third party modbus devices will usually give you a register table, which should explain how to operate the register.
“= 1“ means write value 1 to this register. I’m assuming here that write 1 to turn on the third-party device relay.
Check whether the remote point has a record of recent operations.
If you still can’t find the cause, it could be something else. You can send an email to our sales, tell us your remote assistance Anydesk ID, we make an appointment, we can provide you with remote assistance.