Siargo MF4000 - Communication Parameters; Frame

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5.5.2. Communication parameters
The PC UART communication parameters are listed in table 5.3.
Table 5.3: PC UART communication parameters
Parameters
Protocol
RTU
Baud rate (Bits per second)
38400 bps
Start bits
1
Data bits
8
Stop bits
1
Even/Odd parity
None
Bits period
104.2 µsec
Bytes period
1.1458 msec
Maximum data length
20
Maximum nodes
247
5.5.3. Frame
The frame function is based on the standard Modbus RTU framing:
Table 5.4: frame function
Start_bits
Address
Function codes
Data
CRC
Stop_bits
T1-T2-T3-T4
8 bit
8 bit
N 8 bit (20≥n≥0)
16 bit
T1-T2-T3-T4
Start_bits: 4 periods bit time, for a new frame.
Address: The address can be set from 1 to 255 except for 157 (0x9d). 0 is the broadcast address.
Function codes: Define the product's functions/actions (slaves), either execution or response.
Data: The address of the register, length of data, and the data themselves.
CRC: CRC verification code. The low byte is followed by the high byte. For example, a 16 bit
CRC is divided into BYTE_H and BYTE_L. In the framing, the BYTE_L will come first, then
followed by the BYTE_H. The last one is the STOP signal.
Stop_bits: 4 periods bit time, for ending the current frame.