Rockwell Automation SA3100 Power Module Interface (PMI) Regulator - Manual (Page 58)

5-8 PMI Regulator
Figure 3.7 in chapter 3 shows the analog input circuit. Note that the input impedance
has a finite value of approximately 1.3 megohms. This must be taken into account
when connecting to sources with a high output impedance such as an analog
tachometer scaling board.
Take steps to reduce noise pickup and the possibility of ground loops. In the case of
grounded sources, note the common mode voltage limit. Avoid migrating a remote
ground into the PMI Regulator. Use the differential connections to reduce noise.
Keep input cable lengths as short as possible and ground shields at the source’s earth
ground.
Figure 5.6 – Analog Input - Single-Ended Driven Off Ground
Figure 5.7 – Analog Input - Single-Ended Grounded
+
-
Zout
Vs
Vc
Vcom
-
+
G
Vcom + Vc MUST BE LESS THAN 30 VOLTS
Vs MUST BE LESS THAN 10 VOLTS
+
-
Zout
Vs
Vcom
-
+
G
Vcom MUST BE LESS THAN 30 VOLTS
Vs MUST BE LESS THAN 10 VOLTS