Siemens simatic c7-621 Hardware Installation Manual page 89

7.2 Connecting Loads/Actuators to the Analog Output
Overview
With the analog output, you can supply loads/actuators with current or
voltage.
Cables for Analog You should use shielded, twisted pair cables for analog signals. This reduces
Signals the effects of noise. The shield of the analog cables should be grounded at
both ends. If there are potential differences between the ends of the cable, an
equipotential current can flow through the shield and cause disturbances to
the analog signals. In this case you should only ground the cable at one end.
Abbreviations
The abbreviations used in Figures 7-5 to 7-6 have the following meaning:
Figures 7-5 to 7-6 show how the loads/actuators must be connected to the
current or voltage outputs of the analog output module.
C7-621 / C7-621 AS-i Control Systems
C79000-G7076-C621-01
AO-I: Analog output current
AO-U: Analog output voltage
R : Load/actuator
L
AO-M : Chassis connection (reference potential of the analog output)
L+: Power supply connection 24 V DC
M: Chassis connection of the C7
C7-621 Analog I/Os
7-7