Example of Modbus RTU Frames
Request
Request from the client to the LTMT Modbus RTU server at address 5 to read the L1 RMS current, available in a UINT32 register at address 0x157C.
|
Definition |
Number of Bytes |
Value |
Comment |
|---|---|---|---|
|
Server address |
1 byte |
0x05 |
TeSys Tera Modbus RTU server address |
|
Function code |
1 byte |
0x03 |
Reads n output or internal words |
|
Address |
2 bytes |
0x157C |
Address of the first 16-bit register to read |
|
Number of words |
2 bytes |
0x0002 |
Reads 2 16-bit registers |
|
CRC |
2 bytes |
xyzt |
Value of CRC16 |
Response
Response from the LTMT Modbus RTU server at address 5: L1 RMS current = 87 485 mA.
|
Definition |
Number of Bytes |
Value |
Comment |
|---|---|---|---|
|
Server address |
1 byte |
0x05 |
TeSys Tera Modbus RTU server address |
|
Function code |
1 byte |
0x03 |
Reads n output or internal words |
|
Number of bytes |
1 byte |
0x04 |
Number of bytes to read |
|
Value of words read |
4 bytes |
0x0001 55BD (87 485 mA) |
Reads 2 registers (L1 RMS curent in mA) |
|
CRC |
2 bytes |
xyzt |
Value of CRC16 |