plcbeginner1

plcbeginer1

Lifetime Supporting Member
P
Join Date
Oct 2018
Location
Springtown
Posts
18
Good day,


does anyone have experience on errors 77 78 on deviceNet.


Ii have a Turck assembly that the PLC does not 'see'.
I have it in the scanlist file but for some odd reason it does not communicate with the other devices.
 
Hi, and welcome to the forum. Error 77 says you need to reconfigure your module for the correct transmit and receive data sizes. Which is probably back in your mapping somewhere.
Error 78 says you need to add the device to the network or delete the scanlist entry for that device. Maybe you already have this info. I have a pretty good DNET troubleshooting guide given to me a year or so ago when I was on a large project that used device net.
If you want a copy of it maybe I can zip it and send it to you. Hope this helps.
 
some odd reason
Click to expand...

There's always a reason. The most common ones are bad network wiring, bad network power, bad network length/design, or electrical noise.

But Error 77 in the mix suggests something else; that's a configuration error code indicating that the slave device I/O size doesn't match the number of bytes that the scanner expects. It can't be caused by noise or wiring, though of course noisy networks can also include configuration errors.

Error 77 should never be "intermittent". If it is, then you should replace the device because either its firmware or its storage is failing.
 
Thank you all for responding so quickly!


I have looked up the code 77 and also 78 on Google.
Quick Steps

[FONT=&quot]1. [/FONT]Open the 1756-DNB program and find the properties tab
[FONT=&quot]2. [/FONT]Select the scan list tab
[FONT=&quot]3. [/FONT]Click on the Node that is reporting the error
[FONT=&quot]4. [/FONT]Click the Edit I/O parameters button on the lower left-hand side of the screen
[FONT=&quot]5. [/FONT]Dialog box opens to Edit the I/O parameters
[FONT=&quot]6. [/FONT]The Dialog Box contains 3 sections: Strobed, Polled, or Change State/Cyclic
[FONT=&quot]7. [/FONT]At the Lower Right corner of Dialog Box click the Restore I/O Sizes Button
[FONT=&quot]8. [/FONT]Watch on the Dialog box that the section labelled Polled doesn’t become automatically checked.
[FONT=&quot]9. [/FONT]If the Polled section I/O sizes do not match the Change State/Cyclic section displayed I/O sizes. Toggle the I/O sizes up or down in the polled section to match the I/O sizes in the Change State/Cyclic section.
[FONT=&quot]10. [/FONT]The Scanner Configuration box will appear select YES
[FONT=&quot]11. [/FONT]Return to the Scan List, verify Automap on Add does not have a checked box.
[FONT=&quot]12. [/FONT]Repeat the Check and Map process I/O sizes for both input and output tabs.
[FONT=&quot]13. [/FONT]Toggle to the select start Dword for correct node
[FONT=&quot]14. [/FONT]Select Automap and select OK
[FONT=&quot]15. [/FONT]The Scanner Configuration box will appear select YES (to download changes to device)
[FONT=&quot]16. [/FONT]Verify the machine condition is either cycle stopped or idle mode
[FONT=&quot]17. [/FONT]The Scanner Configuration box will re-appear select YES.
[FONT=&quot] [/FONT]

I found a procedure for the elimination of such(error 77), however I can not seem to get rid of the error.



As for error 78, I think it was because I placed something ( a device) in the scanlist.
Although I have removed it I still get the error ( perhaps I need to de-power the whole PLC?)


I certainly am open to any and all information I can get on the Ethernet/ Modbus/ DeviceNet since I was thrown into repairing such.


My direct email is:
[email protected]


Thanks again!
 
Welcome to the PLCTalk community ! You're in the right place.

If you can save the *.DNT file from RSNetworx for DeviceNet, ZIP it, and post it as an attachment, that will help.

Exactly what kind of Turck device is it ? They make a lot of flexible devices for which the Data size can be tricky, especially the BL20/BL67 I/O platforms.

Power cycles are frequently necessary for master devices to re-initialize. Not necessarily; modern 1756-DNBs can make scanlist changes at runtime, but it can't hurt to reboot the module.

General troubleshooting info can help too; is this a system where you're adding a device, or replacing one, or did the problem just crop up overnight with no changes to the system ?
 
"Book of Knowledge" is the secular name.

My suggestion of "Qur'CAN" was discarded, as was "Zen and the Art of Network Maintenance".
 
Back
Top Bottom