CAS NT-302A - Serial Interface (RS-422;485)

33 / 44
2. Serial Interface (option :RS- 422)
RS-422/485 serial interface is more stable for electric noise effect compare with other communication
method, using electric current difference.
But, install isolated place from Power cable or other electric cables and wires, and please use shielded
cable for better performance.
Recommendable communication distance is about 1.2km.
2-1. Signal Format
①. Type : RS-422/485
②. Format : Baud Rate : Refer “F-function 31”.
Data Bit : 7 or 8(No Parity)
Stop : 1
Parity Bit : Even, Odd, No Parity (Selectable)
Code : ASCII (STX 02H, ETX 03H, CR 0DH, LF 0AH)
1
LSB
0
1
2
3
4
5
MSB
6
0
2-2. Data Format
Same as RS-232C (Refer “6-1. Serial Interface”)
2-3. RS-422 Circuit Connection
Start 1 Bit
Data Bit
Parity Bit
Stop 1 Bit
1.5V Electric
Potential Difference
Rxd(+)
Rxd(-)
Txd(+)
Txd(-)
8 : Txd(+)
9 : Txd(-)
7 : Rxd(-)
6 : Rxd(+)