FORM NO. L-21204-D-0419
10
NETWORK CONNECTIONS
Modbus RS485 Port:
This port is for communicating with
the RSTC1000 using the Modbus RTU protocol over a
2-wire or 4-wire RS485 physical layer (Refer to Figure 10).
Communication Indicator:
Yellow indicator, visible
through top cover, will illuminate whenever the RSTC1000
communicates over the RS485 port.
Communication Error Indicator:
Red indicator, visible
through top cover, will illuminate whenever the RSTC1000
detects an error with a received message.
Figure 10
Modbus RS485 Connections
DC Common
TxB+
TxA–
RxB+
RxA–
1
2
3
4
5
6
DC Common
RxB+
RxA–
TxB+
TxA–
LTR
RSTC1000
PLC or HMI
Four Wire RS485 Connections
LTR
DC Common
TxB+
TxA–
RxB+
RxA–
1
2
3
4
5
6
DC Common
Non-Inverted Tx/Rx
Inverted Tx / Rx
RSTC1000
PLC or HMI
Two Wire RS485 Connections
+24 VDC
DC Common
TxB+
TxA–
RxB+
RxA–
1
2
3
4
5
6
Red
Black
White (RxB+)
Yellow (RxA–)
Blue (TxB+)
Orange (TxA–)
RSTC
ROP
ROP - RSTC
LTR
Termination resistors added externally
- Recommend 150
Ω
, 0.5 W
LTR = User supplied line termination resistor
Cable Recommendation:
- Shielded
- 24 awg is always sufficient
- 4 wire system, 1000 m (9600 baud)
- 2 wire system, 500 m (9600 baud)
Figure 9
RSTC1000
R
ST
C1000
USB
RS485
Power Indicator
Reset
Communication Error
Indicator
Communication Indicator