Older Version 7.6.6 and CompactLogix V20

I have a site that has worked fine for years using 7.6.6 that is connected to a ControlLogix V20 based Gateway and my customer just swapped out a SLC 5/04 DH+ device with a CompactLogix L30ER V20 firmware. I can setup up the device, it connects fine showing Connected: EIP - Run Mode. I can use the Quick Client to browse the processor tags fine, but when I try to Read or Subscribe from the Quick Client I get a valid Timestamp, Status:Unknown / Value:null / Quality: Uknown. I am working on upgrading them to 7.9 today but I need to try to get this device working temporarily while all of the POs go through. I know there are issues with 7.6 regarding Logix V21 and higher, but I would have thought that the included Allen-Bradley CompactLogic - Connect To CompactLogix firmware v20 and prior processors should work. Any ideas ?

Let me guess… it’s firmware v20.15 or higher?

Rockwell disabled the direct memory access method in later revisions of firmware 20. The latest one that I know for sure works with the old Compact/ControlLogix drivers is 20.11.

I can’t get online with it directly from here but just using a Browser to the IP Address it says

1769-L30ER/A LOGIX5330ER
Product Revision 20.019 Build 98
Firmware Version Date May 28 2015 14:41:59

Yeah… 20.19.

You’ll need to upgrade and use the Logix v21 driver. The performance will not be good since it has to read using symbolic addressing instead of DMA or instance-based.

Alternatively, you can use RSLinx or Kepware and make an OPC connection, if upgrading Ignition isn’t an option there.

You could also temporarily downgrade the firmware.

Thanks guys - not my equipment so firmware downgrade is probably not an option. I may give RSLinx a shot for a temporary band aid, but I guess I’ll have to try to speed up the upgrade process.