Message read from ControlLogix


I am curious if there is a way to perform a message read from a ControlLogix PLC to an Opto snap-up1-ads. Currently there are ~32 analog inputs wired to the up1-ads that I need to get into the Logix PLC.

I do not have the program file(s) for the up1-ads, but I am able to see the configured point names through ioManager / Inspect I/O Unit. Is there a way to set up a message instruction in the ControlLogix to read this data? What worries me is the firmware appears to be quite outdated:

0xFFFF F030 0018 Loader Version R3.0d
0xFFFF F030 0000 Memory Map Version 1
0xFFFF F030 001C Firmware Version R1.0n
0xFFFF F030 00A0 Firmware Version Date 08/12/2002

Thanks for any input,


Hello Ryan,

Thank you for your participation in Opto 22’s Forums!

Only the SNAP-PAC Ethernet interfaced family of controllers and I/O units (firmware version R8.3 and later) are capable of operating as remote I/O to Allen Bradley ControlLogix and CompactLogix PLCs. MicroLogix (1100-OS2 or 1400) and SLC 5/05 PLC’s are capable of messaging the SNAP-PAC family for I/O data.

Here’s a link to our IO4AB page so you may see what we offer…

Here’s an essential question. In your PLC implementation, do you intend to allow the logic within the SNAP-UP1-ADS to continue operating or do you wish to migrate the control from the SNAP-UP1-ADS into the PLC?

If you need to allow the UP1-ADS to operate its control logic (since you don’t have a copy of the strategy), you could add a SNAP-PAC-R2 (and associated hardware) on the same control network to scan the I/O states of the SNAP-UP1-ADS. You will create an EtherNet/IP assembly on the SNAP-PAC-R2 the PLC could scan.

If you could reproduce the control logic (or you located a copy of the strategy), you could replace the SNAP-UP1-ADS and the rack with a SNAP-PAC-R2 and a “PAC” series rack (you may continue to use the same I/O modules).

If you intend to use the PLC to replace the control logic of the SNAP-UP1-ADS, you may replace the rack and the SNAP-UP1-ADS with a SNAP-PAC-EB1 and a “PAC” series rack. You do not need to replace the I/O modules. Create an EtherNet/IP assembly instance to allow the PLC to scan the I/O.

Some tidbits on the Allen-Bradley implementation… Only Logix PLCs with v13 or later are supported. We also ask for you to use an EtherNet/IP module such as a 1756-ENBT/2 or the newer 1756-EN2x units.

Here is a potential “gotcha” too. Please ensure that your entire Ethernet control network is IGMP Snooping AND Querying capable or you’ll end up having odd problems due to multicast flooding of the network. Please note that products such as N-Tron’s 500, 700, or 7000 series devices are designed for this very implementation.

If you have any specific question, our pre-sales engineering group is always available to help.