Hey Rafi,
The model option overrides any settings in the sequence file. Therefore, since you set parallel in the model options then ALL sequences will run with a parallel synchronization. Try setting it to One Thread Only and you will see that only one thread executes. I assume this is expected behavior. You want to set the model options to Don't Synchronize and uncheck the Sequential Batch Mode. Then the Synchronization steps will work as expected. Otherwise they get overridden.
Let's assume you have a sequence that is executing 3 sockets. The first 4 steps of your test can execute in parallel. The next 2 you want to execute in serial (i.e. 1st socket executes both steps, then 2nd socket executes both steps, then 3rd socket executes both steps). Then you have 4 more steps that all sockets can execute simultaneously. Suppose each of the 10 steps takes approximately 1 minute to execute. If you have your setting in the Model Options to be Sequential Batch Mode you will find that the total test time = 30 minutes. This is because one socket executes the entire test then the next one takes it's turn. If you have that setting turned off in the Model Options and you have a Synchronization section (i.e. a Batch Synchronization step that starts a Serial section for those 2 steps that have to execute in serial) then your entire test will only take 14 minutes to execute. 4 minutes for the first 4 steps. 6 minutes for each socket to execute the 2 steps serially. and 4 minutes for the last 2 steps. This decreases your test time by more than half. I'm attaching a demo of this. Except instead of minutes it uses seconds. Don't click the OK button on any of the dialogs that popup. They will close after they have been open for 1 second.
1- Open the Sequence that's attached
2- Configure Model Options with the Sequential Batch Mode options checked. Also set it to use 3 test sockets.
3- Run the sequence at it should take about 30 seconds.
4- Configure the Model Options with Sequential Batch Mode unchecked and the drop down set to Don't Synchronize
5- Run the sequence and it should take about approximately 14 seconds. It may be a little more because of the multithreading.
The other pitfall/advantage, depending on how you look at it, to setting this option in the Model Options is that everyone using that station is forced to execute whatever you set in there.
Hopefully this will help clarify a little. This is just information only. I'm not saying that setting the Model Options is bad. If that's what you ultimately want as the developer then it's your decision. It all depends on what you want. I personally prefer the synchronized sections inside of the sequence because then it is not limiting to other sequences running on the station and if you have a whole bunch of people writing sequences then they are given more freedom.
If you want more info on the 3 synchronized sections look in the TestStand help under Batch Synchronization Enumeration. Or look in the TestStand manual:
http://www.ni.com/pdf/manuals/322016b.pdf starting on page 11-56 at the bottom and go until page 11-61. There are some caveats pointed out in there.
Let me know if you have any more questions or need clarification on anything.
Regards,