Rice Lake PR5230 Fieldbus Transmitter - Manual (Page 168)

J-Bus/ModBus Protocol PR 5230 Instrument Manual
EN-168 Sartorius
6.2 ModBus-RTU
A serial interface is used for connection.
The telegram consists of four blocks:
Addr
8
Func
8
Crc
16
Legend
Addr
8
Slave device address within 1…126
Func
8
Function code
For further data, see Chapter 6.4
Crc
16
Checksum of all preceding characters
Note:
A telegram sent to Slave 0 is executed by all ModBus participants, but replied by none of these
devices!
At 9600 bauds, the reply time is typical 4 ms and maximal 8 ms.
A faulty command received by PR 5230 (e.g., parity error in the data, or CRC error) is ignored and no reply is
sent.
The pauses between the individual characters and a command must not exceed the 3.5-fold value of a
character length; otherwise PR 5230 detects a premature end of the command.