Control – connection, PLC and signal processing

On this page, you may find information concerning:

  • General composition of a Pick-to-Light system
  • Connecting the system
  • Signal processing during working processes

General composition of a Pick-to-Light system

P2L digital

The digital P2L-sensors are parallel connected to the PLC via I/O using 6-terminal M8 connectors (not included in delivery). They are then supplied with power from the SPS.


Digital P2L sensors parallel connected PLC with I/O MFR for

  • Control of assembly sequence
  • Control of the Containers
  • Visualizing etc.



P2L CAN bus

The P2L sensors with CAN bus are connected in a row by a cable with 4 pins M8 connector (not included in scope of delivery)using only one line to the CAN bus module of the PLC. Up to 100 sensors can be connected in a system. The P2L sensors are supplied with power by the CAN bus line.


P2L sensors with CAN bus in a row


PLC with I/O MFR for

  • Control of assembly sequence
  • Control of the containers,
  • Visualizing etc.


P2L digital


P2L CAN bus


Signal processing

Die grüne LED leuchtet. Wird in das fach darunter gegriffen, erlischt die LED.
LED signals during correct picking
Die grüne LED ist aus und es wird in das Fach darunter gegriffen, dann blinkt die rote LED zwei Mal.
LED signals during wrong picking

P2L digital

In einem Schema werden die Signallevel am Set und Pick Indikator dargestellt.
PLC signals during correct picking operation
Das Schema zeigt, dass kein Signal am Pick Ouput Kontakt des Sensors anliegt, der Pick Input aber ein Signal erhält und somit auch ein Error Output erzeigt wird.,
PLC signals during picking error

P2L CAN bus

CAN – Data Telegram

P2L CAN Bus uses CAN protocol 2.0 A.

Auflistung des P2L CAN Bus Datentelegramms
CAN bus data telegram of the P2L C001

Message Protocol

The sensor transmission rate is 125 kBit/s. The data block uses only one Byte of data, meaning 8 of 64 bits are used.

Signals sent to the sensor and functions

Command Description
0 Turns the LED off and ends the teach-in procedure and the picking modus
1 Begin teaching
2 Picking operation started
3 Turns red LED on
4 Turns green LED on
5 Turns green and red LED on
6 Sensor reachable? If yes: answer with 200
7 Switches LEDs off, which were on. Does not overwrite any picking or teach-in operation

When a picking message is delivered, the corresponding command will be executed and the green LED lights up. The picking signal and teaching signal have higher priority.

P2L sensor answers

Command Description
128 Sensor teaching process has taken place
129 The piece got picked while in picking modus
130 Error
200 Signal answer of the sensor while it’s reachable

LEDs at P2L sensor show the actual operation status. In case of a picking error during assembly or an error during teaching-in procedure, the red LED blinks periodically.