81
Fig.29. Method of connecting the RS-485 interface
The PC card transmission line marking depends on the card
manufacturer.
5.9.2. MODBUS protocol description
The implemented protocol complies with Modicon’s PI-MBUS-300 Rev
G specification. PCE-P30U MODBUS protocol serial interface parame
-
ters :
•
Transducer address 1..247.
•
Transmission rate: 4800, 9600, 19200, 38400, 57600, 115200,
230400, 256000 [b/s].
•
Operation mode: RTU with the frame format: 8n2, 8e1, 8o1, 8n1.
•
Maximum time to start response: 200 ms (the response time may
get longer up to 500ms during saving the data to the SD/SDHC
card).
Serial interface configuration consists of setting the transmission rate,
device address and the information unit format – protocol.