Siemens PPU 26x.3 series Manual page 136

Connectable components
7.3 MCP Interface PN
All keys signal "high" in the idle state (= open). When actuated, the state changes to "low".
Short-stroke keyboards and membrane keyboards can be connected. 5 V signals can also be
applied to the inputs. The inputs are TTL-compatible, but not 24 V-tolerant.
Figure 7-17
Note
LED brightness
The setting of the LED brightness can be implemented by an additional external resistor
connected in series.
Connector designation:
Connector type:
Special feature:
Max. cable length:
136
Schematic circuit diagram X111
X111, X112, X113, X114
40-pin plug connector
No galvanic isolation, with interlock
2 m
PPU and components
Manual, 10/2015, 6FC5397-2DP40-5BA3