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Reference Number: AA-02123// Views: AA-02123// Created: 2023-01-11 16:20:40// Last Updated: 2023-01-11 17:18:23
Problem & Solution
No sync signal unless the audio cable is loosened

Problem

On trying to synchronize an external device (slave) with my OPAL-RT simulator (master), I find that the external device does not receive the synchronization signal (clock signal) unless I loosen the audio cable.

However, this set up is unstable, how do I fix this to work such that the connection is tight?

Solution

When we want to connect any external device to receive the synchronization signal from our OPAL-RT simulator, we must check these points:

- What should be the type of synchronization signal: Audio or Optical?

- What is the setting in OPAL-RT Boards or OpCtrl block in the model that is being run on the simulator?

If the external device has to be synchronized using an audio cable then we must select the option "Audio" in OPAL-RT Boards or OpCtrl block.

Proper setting of the option "Type of generated synchronization signal" in OPAL-RT boards (as shown below, when an audio cable must be used, we must have this option set to "Audio")





When you are using OpCtrl block:




Most often, if this point is missed (default setting is Optical so we must be careful to change that if required), there will be a reverse polarity signal that appears on the TX audio port of the simulator.

Therefore when the audio cable is properly connected we would not get any signal. However loosening up the cable will cause the sync, signal to be received. If you find yourself in this situation, please double check the model settings.

The synchronization must work without us having to loosen up the audio cable.


The synchronization signal as observed from the TX audio port when we have the proper "Audio" setting is:



The image shown above is what you want the synchronization signal to look like when using an audio cable.

Here the oscilloscope probe is connected as shown below: 




However, when we DO NOT select "Audio" in OPAL-RT Boards or OpCtrl, then this signal on the TX audio port of the simulator looks like this (reversed polarity):




For additional details on synchronization using an audio cable please also see this article:

Problem with Synchronization card using audio cable