This document explains how difficult operational “Out of sync” issues can occur when working with the SIEMENS Inspekto VIS system’s Sequence feature and a control device (such as a PLC, robot/cobot, or MES) to control the system connectivity. It presents alternative ways of working with the SIEMENS Inspekto VIS system when integrated with a control device.
What is Sequence?
A sequence is a set of profiles in the SIEMENS Inspekto VIS system grouped together to create a multi‑step inspection process. It is used to pre-set rules that automatically determine what the system will do if an inspection result is OK or NOK (i.e., if NOK, repeat the inspection).
A sequence is required when several steps are needed to perform a full product inspection, for example, in a manual assembly task or a part that needs to be inspected from different angles.
Sequences are intended only for manual inspection when the user interacts directly with the system.
What is Connectivity?
Connectivity is a set of protocols that allows the SIEMENS Inspekto VIS system to communicate with a device to receive commands and report results.
The SIEMENS Inspekto VIS system supports the following connectivity methods: Profinet, Ethernet/IP, TCP/IP, Digital I/O, and Discrete Digital I/O.
When working with any of the above Connectivity protocols, the control device (i.e., PLC, MES, Cobot/Robot) can send commands to the SIEMENS Inspekto VIS system to load profiles, change inspection modes, start a new batch, and trigger a new inspection.
After every command is received and processed, the SIEMENS Inspekto VIS system sends responses to the connected device, including the last command status, inspection results, and errors.
For more details on the different Connectivity modes supported by the SIEMENS Inspekto VIS system, refer to the relevant connectivity integration manual, which you can find at MySIEMENS Inspekto VIS.
Why Connectivity does not support Sequence?
Let’s assume we have a sequence of 4 profiles:
In this Sequence:
Step 1 is configured to continue to the next step regardless of the inspection result.
Step 2 is configured to restart inspections from step 1 if the result is NOK.
Steps 3 and 4 are configured to repeat the inspection with an NOK result until an OK result is obtained.
Manual operation of the Sequence is not a problem. Users can see the results of each step in the user interface and react to the presented situation. If step 2 reports an NOK result, users can make the necessary changes and re-position the needed parts to restart the test from step 1.
If step 3 or 4 reports an NOK result, users can correct the issue in the needed step and repeat the test using the system’s user interface.
Operating the Sequence using a control device complicates the process:
The control device sends a “Start Sequence” command to the SIEMENS Inspekto VIS system.
The SIEMENS Inspekto VIS system inspects the part in step 1 and continues to the profile in step 2 regardless of the result. If an NOK result is found in step 2, the SIEMENS Inspekto VIS system must restart the sequence from step 1 and send a “Sequence failed” response to the control device. However, the control device will not know how or in which step it failed.
If the inspection can continue to step 3 but obtains an NOK result, the system must wait for another inspection trigger. However, the control device will not know what step the Sequence is in.
This situation will cause the control device to get out of sync with the SIEMENS Inspekto VIS system (for example, the control device thinks that the Sequence is in step 4, but it is actually in step 3).
Even if the SIEMENS Inspekto VIS system reports a result after every inspection but does not also state which step it is in, the “out of sync” situation will inevitably occur.
In the above example, you can easily solve the “out of sync” situation by allowing the control device to:
Obtain information on the SIEMENS Inspekto VIS system’s current profile.
Obtain results and responses for each step (per profile).
Override the Sequence and load a specific step.
The three steps above require the control device to be able to control each profile of the Sequence separately, in addition to controlling the Sequence. Suppose the PLC must control each profile separately. In this case, there is no value in adding the ability to control a sequence because controlling each profile means that the controlling device has already created the equivalent of a sequence, but it is managed by the control device instead of the SIEMENS Inspekto VIS system.
This means that the control device, rather than the SIEMENS Inspekto VIS system, will create the Sequence when using Connectivity. This will allow it to maintain control of the process and will not cause it to lose any capability that exists in the Sequence.
The control device can handle the example shown above in the following way:
The control device sends the Load profile 1 command.
Receives “Profile loaded successfully” response.
The control device sends an inspection trigger command.
Receives inspection result (OK/NOK).
The result does not matter in this step; the rule is to continue to next step regardless of the result.
The control device sends the Load profile 2 command.
Receives “Profile loaded successfully” response.
The control device sends an inspection trigger command.
Receives inspection result:
If OK, proceed.
If NOK, go back to step 1.
The control device sends the Load profile 3 command.
Receives “Profile loaded successfully” response.
Controlling device sends inspection trigger command.
Receives inspection result:
If OK, proceed.
If NOK, resend inspection triggers until the result is OK.
In these cases, operator intervention in the line is usually required to address the issue.
The control device sends the Load profile 4 command.
Receives “Profile loaded successfully” response.
The control device sends an inspection trigger command.
Receives inspection result:
If OK, the control device has registered the cycle as successful.
If NOK, resend inspection triggers until the result is OK.
In these cases, operator intervention in the line is usually required to address the issue.