1747-SDN error 77

Mark@GBW

Member
Join Date
May 2017
Location
Bjerringbro
Posts
13
Hi everyone, first time posting here.

I have a problem with 1747-SDN devicenet scanner, connected to 3 Numatics G2-2 valve modules. We had a fault where node 1 would turn on all solenoids when the output power was applied, so we tried swapping a few parts around to see if we could pin down the fault. No success so we put everything back and ordered a new comms module for node 1. We had an original .dnt file and EDS file for the network so we downloaded that again and now we have error 77 on nodes 1 and 2. The comms modules for these nodes have newer firmware than original (looks like node 2 has been replaced some time in the past), could it be that I need a newer EDS file for the newer comms modules as the I/O's shouldn't have changed?
 
Welcome to the Forum!

A displayed Error 77 for any 1747-SDN module is explained as :'Data size expected by the device does not match scanlist entry.'.

The recommended mitigation is:'Reconfigure your module for the correct transmit and receive data sizes.'

Any difference in Firmware level between the original vs. existing setup could mean a different 'I/O footprint'; acquire the existing devices' EDS files and register (re-register) them on the PC running RSNetworx for DeviceNet.

Upon completion edit the .dnt file and replace the original devices with the existing one while maintaining the same I/O mapping; I'd create a new file and work side-by-side-with the old one.

When done, download to the Scanner.

Use the resources from within http://literature.rockwellautomation.com/idc/groups/literature/documents/um/1747-um655_-en-p.pdf
 
"77 Data size expected by the device does not
match scan list entry.
Reconfigure your module for the correct
transmit and receive data sizes"

In RSNetworx: Do a complete upload of the network. Right click your devices (node 1-2) and properties. There should be a tab telling you how many bytes are transmitted for each type of communication (cyclic, COS, polled). Compare to other nodes.

Go to properties of your scanner, and scanlist. Compare how the configuration is setup. (I believe there is an "I/O" button that needs to be pressed on the Scanlist page that will bring a window showing how many bytes are configured for each type of communication.)

The bytes the scanlist is expecting needs to match what the device is sending. I don't know if this valve module has any configuration internally to change how many bytes it's transmitting.

RSNetworx / RSLinx will allow you to download the EDS from the device, if the device shows as "unknown"
 
Hi, thank you for your quick replies, happy days (y) we have cleared the fault 🍻

We ran through the I/O footprint comparing the offline .dnt file to the current uploaded data on the nodes which have error 77 on them.

After scrolling through various parameters we came across a few variant.

Within the scanner module properties list >
scanlist >
edit I/O parameters [of node1].

We found the change of states input size was 0 instead of 16, this was the same for node 2. Both nodes we had error 77 on.

After downloaded the new parameters and cycling the power the faults on the nodes have cleared.
 
Hi Mark, do you mind to share the EDS file for G2-2 Numatics Devicenet module. I have encountered same error 77 at 1756-DNB as well when changed in G2-2 at node 1. However, I have checked all the configuration especially the input size and output size is the same as previous. Thus need your kindness to share the EDS file
 
Hi Adrian. Could you ever manage to obtain a Devicenet EDS File for a Numatics G2-2 Valve Bank? Please share as I also need it to resolve an E77 error on a Rx/Tx Mismatch on a 1756-DNB. Thanks.
 

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