# Industrial Communications Signals

The SnAPP utilizes a fixed set of pre-named signals which can be used to transfer data and results to and/or from a PLC and the vision sensor.

To control triggering from the PLC with the trigger control and status signals, the Trigger Mode must be set to Single.

Note: The signals are shared between the supported protocols, however, they are mapped into the systems differently. For the specifics of the signal mapping for each protocol, see the following topics:

- Ethernet/IP Input and Output Assembly Objects
- PROFINET Module Reference Table
- SLMP Control and Data Blocks

Input Assembly | Signal | Description
Acquisition Error | This bit is set when an SnAPP fails to acquire an image for one of the following reasons: The SnAPP is currently acquiring an image. The SnAPP is out of image buffers. This bit is cleared when a successful acquisition is triggered.
Acquisition ID | This ID increments on the completion of every acquisition, regardless of the trigger source, and can be used to synchronize an acquisition with its Inspection Result. The Acquisition ID is changed on the start of an acquisition. The Acquisition ID is changed on the end of an acquisition. If the PLC is the trigger source, the Acquisition ID is set prior to setting the Trigger Acknowledge bit.
Command Completed | This bit is set when the command execution is completed, and cleared when the Execute Command bit has been cleared.
Command Executing | This bit is set while a command execution is in progress.
Command Failed | This bit is set on the completion of a command, if the command has failed to execute successfully, or if an unknown Command ID was set.
Error | This bit is set when an error has occurred, which is defined in the Error ID field.
Error ID | See Error ID codes.
Inspection Completed | This bit is toggled upon the completion of an inspection.
Inspection Image ID | These bytes are used to provide the acquisition IDs for each of the images associated with this set of results.
Inspection ID | The acquisition ID associated with this set of results.
Inspection Passed | This bit indicates the pass and/or fail state of the inspection.
Inspection Results | For more information about the Inspection Results, see the Inspection Results.
Results Valid | This bit is set when the Inspected Image ID, Inspection Result Code and Inspection Results fields are valid. The bit is cleared when the Inspection Results Acknowledge bit is set.
Trigger Acknowledge | This bit indicates when an SnAPP is successfully triggered via the Trigger bit. The Trigger Acknowledge bit stays set until the Trigger bit is cleared.
Trigger Ready | This bit indicates when an SnAPP can accept a new trigger via the Trigger bit.
Current Program ID | These bits indicate the current program number. A program ID is a 16 bit number from 1 to 20.
Output Assembly | Signal | Description
Clear Error | When this bit is set, it clears the Error and Error ID signals; the Clear Error bit need to be held high until the Error bit is cleared. If an error is queued, clearing this bit causes the Error and Error ID signals to be set to the next queued error code.
Execute Command | When the Execute Command bit is set to high, the Command ID signal is read by the vision sensor and the associated command is executed. The signal must be held high until the Command Completed bit is set. Once the Command Completed bit is set, clearing the Execute Command bit also clears the Command Completed bit.
Command ID | This field indicates the program number between 1 and 20 that will be executed on the rising edge of the Execute Command bit. This signal should not be changed until the Command Completed bit has been set. 0: Reserved 1-20: Program number 21-65535: Reserved
Inspection Results Acknowledge | The Inspection Results Acknowledge bit acknowledges that the PLC has received the Inspected Image ID, and Inspection Results data.
Trigger | Setting the Trigger bit will trigger an acquisition on the vision sensor.