New DNP3 Module Read After Operate Not Working?

Ignition
1

I'm not saying this setting isn't working, but I thought it would fix the issue.

The issue is the value of my DNP3 analog output tag is always one behind.

I have a test tag (memory) with a value changed script that writes the value to a DNP3 analog output (OPC item path) tag each time the test tag value changes. The value of the DNP3 analog output tag always shows the previous value. I know the output is working because I'm monitoring the address in the RTAC, it shows the same value as the test tag (so I know the output is working).

Here's a little sequence if my previous explanation is poor.

test tag value:        1, 2, 3, 4, 5, 6, 7, 8
DNP analog output tag:    1, 2, 3, 4, 5, 6, 7
RTAC tag:              1, 2, 3, 4, 5, 6, 7, 8

The device configuration includes:
Command Mode - DIRECT_OPERATE
Read After Operation - TRUE

Is there something I'm missing in my configuration?

Side note - this doesn't happen with the Legacy DNP3 driver and the same RTAC.

Ignition v8.1.37
New DNP3 Module v1.1.38.2024030513

2

Wireshark capture?

Maybe the RTU takes a little too long to execute and the read-after-operate ends up reading the old value. 8.1.39 has a new setting to insert a configurable delay before the read-after-operate is issued.

1 Like
3

I can't share the packet capture (need to keep the IPs hidden), but here are some screen shots. Apologies if its hard to follow.

@Kevin.Herron It looks like you nailed it.
What delay does the legacy driver use?
When will 8.1.39 be released?
The RTAC is an SEL-3505. Not an expert on this but I'll look for some settings.
Thanks Kevin.

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4

The legacy driver doesn't issue an explicit read-after-operate, but it was probably explicitly polling that point as a consequence of how the legacy driver operated, so you eventually saw the update.

The new driver is using class-based polling by default, and read-after-operate is a hack for outstations that don't generate an analog output event with the new value after the operation completes.

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5

Kevin, when is 8.1.39 scheduled to be released? I am having the same issue.

6

As soon as April 9th, though no sooner.

7

Thanks! I am excited to test it out.

8

Thanks! I set the "Read After Operate Delay (ms)" to 1000 ms for the analog output point and it's working well.

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