ControlMaster CM10, CM15, CM30 and CM50
Universal process controllers and indicators,
1
/
8
,
1
/
4
and
1
/
2
DIN
5 MODBUS Communications
16
IM/CM/C–EN
5.4 Pull-up and Pull-down Resistors
To prevent false triggering of slaves when the master (host computer) is inactive, pull-up and pull-down resistors must be fitted
to the RS422/485 interface in the host computer.
Resistors are normally connected to the interface by hard-wired links or switches – refer to the manufacturer's instructions
5.5 Termination Resistor
For long transmission lines, a 120
termination resistor must be fitted to the last slave in the chain – see Fig. 5.2.
Fig. 5.2 Connecting Multiple Slaves
14
15
16
17
18
14
15
16
17
18
CM10, 15, 30
CM50
CM10, 15, 30
CM50
19
20
21
22
23
19
20
21
22
23
Rx+
Rx–
Tx+
Tx–
COM
Host
Computer
Tx–
Rx+
Rx–
COM
Tx+
Tx–
Rx+
Rx–
COM
Tx+
Last Slave
First Slave
120
Termination Resistor
Standard
Connections
Standard
Connections
Master
