Westermo RM-115S - Manual (Page 16)

115S Serial I/O Module User Manual
Page 16 June 2011
2.2.3.2 Floating Differential Mode mA Inputs
Differential mode current inputs should be used when measuring a current loop which
cannot be connected to earth or ground. This allows the input to be connected anywhere
in the current loop. Common mode voltage can be up to 27VDC.
Up to four loops can be connected, to terminal pairs [AIN1-AIN2], [AIN3-AIN4],
[AIN5-AIN6], [AIN7-AIN8] - the former terminal is +ve and the latter –ve.
The diagram in Figure 2-8 indicates how to connect devices for differential mode current
inputs.
Figure 2-8: Connections for differential current inputs.
Note:
- The module configuration needs to be changed for this type of input
- To change the input configuration, refer to section 4.4
WARNING !
Ensure correct DIP switch positions AND software configuration has been
completed for each analogue input BEFORE connecting external signals to the
115S-12 module.
V-
AIN3
AIN4
AGND
115S-12 Module
ALS +24V
Externally powered
sensor
+ -
AIN1
AIN2
+
-
Loop powered
sensor
Power
supply