Devicenet Error Code 72

I'm struggling with a devicenet network that experiences Error Code 72.
I have a node (Koyo DVNTS gateway) drop off line, & it goes to error code 72.
I've been through & checked grounding, terminating resistors, & cabling routed away from high voltage sources.
Any ideas what I should be looking at?

Bump

After the node drops off does it come back online shortly thereafter? Does it keep cycling offline and online at a random interval?

Try increasing the Interscan Time Delay.

Code 72 = I/O connection timed out or stopped responding

You really need DeviceNet Guru Ken Roach here

You should really post more info as well, like what plc and details about the network!

1756-DNB, CLX PLC.
Automationtdirect DVN gateway.
3 AB VFD, (2 powerflex 40, 1 powerflex 70)

Yes, it cycles online & offline at random intervals.
I've increased the interscan delay, & we'll see where that takes us.

Increasing the Inter-Scan Delay will reduce how often the Koyo adapter receives a poll from the 1756-DNB Master. I have seen some inexpensive devices that can't handle a fast poll.

The presence of AC drives makes it more likely that there is some induced noise, so be diligent with the grounding, shielding, and termination checks. Do not rely on visual inspection; get out a meter and measure for 60 ohms between blue and white when the power is off.

Extremely important: do not use the DeviceNet power supply for any other loads. Even if it's tempting.

Do the A-B drives ever drop offline and give you an error 72 on the scanner ?

The 1756-DNB/C can give you some low-level diagnostics; see the RA Knowledgebase document 50064.

Thanks Ken.
No other devices on the network give a 72 on the scanner, but this one has some analog IO where the other Koyo is digital.
I've been very diligent with my grounding, & my termination resistors as well. I ring out at 60.3 ohms with power off & I'm not using the DVN power supply elsewhere, I've got a seperate 24 V for that stuff.

It's been an hour or so, & no faults yet. Crossing my fingers (faults were 4-5 an hour before hand).

This is only conjecture: maybe the Koyo adapter with Analog modules requires more time to put together an I/O assembly and therefore cannot keep up with a fast poll.

You could get to the bottom of it with some tests on Interscan Delay or Background Scan, and a DeviceNet traffic analyzer, but maybe just a qualitative test is OK for now.

Is this the F2, the D0, or T1K- DEVNETS adapter ?

T1K- DEVNETS

It's got the be the interscan delay, because when I crank it down, boom, it faults like clock work.

When I open it up a bit (the RPI of this IO isn't that important, certainly not in the 10mS range for this project) it vanishes.

CroCop said:

T1K- DEVNETS

It's got the be the interscan delay, because when I crank it down, boom, it faults like clock work.

When I open it up a bit (the RPI of this IO isn't that important, certainly not in the 10mS range for this project) it vanishes.

Click to expand...

is it OK now? you did change the power unit and increase interscan delay,right?

Good morning, "qiucs", and welcome to the PLCTalk forum community !

This forum software doesn't have a good method for archiving posts or threads or preventing them from being resurrected and updated, even after many years. If you look carefully, that thread was started in 2009.

It's possible that the original poster is still around and remembers the resolution (heck, I'm still here) but don't be surprised if they don't.

What might work just as well or better is to go to the main Q&A page and use the big green Start A New Thread button.

You can copy the URL of an old thread for reference, e.g. "I have a problem similar to this user a while ago" then add context and differences and details about your own system.

Again, welcome to the PLCTalk forum community !