Cause

No sensor can be determined for the PLC Input during target tracking. The cause for this can be an incorrect type of signal at the PLC input and/or at the sensor. The target tracking definition might also be missing at a terminal or plug upstream of the sensor.

Solution

1. First double-click the PLC input and select the Symbol / function data tab in the Properties <...> dialog.
2. Click [Logic].
3. Check the Type of signal property for the PLC input in the Connection point logic dialog. This property must match the function definition! If, for example, you entered a PLC connection point with the function definition "PLC connection point, DI" or "PLC connection point (fluid), DI", the type of signal field must be set as a "Digital input".
4. Also check whether the type of signal property on the sensor is set to "sensor".
5. If a terminal or a plug is located between the sensor and the PLC input, also check the setting in the field Target tracking (PLC) to for this object. A "2" must be entered for the function connection point 1 and a "1" for function connection point 2.
6. Refresh the connections and then start a new check run.