User manual

85
Version 2.4 (10/2011) en
Original instructions
Drum Motor
Options and accessories
Worst case connection Worst case connection of a NPN open-collector output encoder to a PNP
input unit
Typical configuration for a PLC with inputs:
• High-Active
• PNP signal level
The circuit shown above does not meet the signal level requirements under any
circumstances. The causes are as follows:
• It is difficult to size the external load resistor to avoid overstressing the
encoder output while at the same time ensuring a correct high voltage level at
the input unit.
• This results in a significant decline in the signal-to-noise ratio.
The encoder should thus be connected to the (PLC) input as shown in the
"Best connection" diagram (see above).
R
LE
R
LI
External Load Resistor
Internal Load Resistor of the input unit
+ V = Operating Voltage
PLC
Encoder Input
R
LI
Load Resistor
R
LI
Load Resistor
0V = GND
Signal B
Signal A
Encoder
R
LE