ADP3450- Trigger timing between multiple devices, across multiple PCs, over a network

[JBoaz]

I am trying to use 18 ADP3450s simultaneously in record mode to capture a large amount of data over a 1 min period. I have split control of the scopes across 3 different computers. Scopes are being controlled over a network.

When testing to make sure that each of the scopes were capturing the same 60s of data, I tied the triggering signal to ch1, to see where things lined up. What I found is that each time the scopes were triggered, at least one of them displayed the triggering signal over 30s past when the trigger was meant to occur, while all others looked as expected. The scope that displayed this unexpected behavior is different every time the setup is triggered.

My question is, what is causing this timing difference, and how can I get them looking the same?

Scope Settings

• Each scope is configured to capture 1 minute (6s/div) of data with 10% pre-trigger, at 1Mhz for a total of 10MS.
• Each scope is using external trigger 1.
• The signal used to trigger scopes is also tied to ch1 of each scope (This is just for debugging the timing. I will need all 4 channels for data collection during my application)
• Triggering on a rising edge
• The trigger mode is set to 'Normal' not 'Auto'

Setup

• Computers and scopes are connected via Ethernet cable and network switches to a Synology NAS 
• Computers are running windows 11
• Computers and scopes are all on the same network
• Triggering signal is coming from a waveform generator, going to a fanout clock buffer, then to the external trigger of the scope. There are 3 clock buffers, each buffer has 8 outputs. 6 are connected to external triggers, the others are used as the ch1 signal I am using to debug.

Images of an expected timing of the signal and the unexpected timing of the signal are attached.

[attila]

Hi @JBoaz

With newer software version you can use normal (repeated) for deep up to 128M samples capture. The record is for even longer captures, uses data streaming which is limited by the data connection, not fully reliable.
Make sure the trigger signal is generated only after all devices armed, after each is configured and past the 6 second prefill (10% of 60s). If the signal is during this time some devices may trigger and other only on the next event.
Depending on your requirements, you could also generate the trigger signal by one of the ADPs which configured/started lastly.
To better synchronize devices at higher frequency, to eliminate jitter you can use reference clock option. This may not be relevant for 1MHz captures.