I have been looking for the same thing:
I started working with Schneider PLCs and they have Ethernet/IP support now. Trying to make connections to AB Logix controllers has been a challenge - I have seen no support for any AB controller to be a Class 1 Implicit slave so communication is always one-way - from the AB PLC as the scanner to the Schneider hardware as adapter (which supports both adapter and scanner functionality).
I have only found the following ways to communicate with the Logix5000 programmed controllers as a server:
1. Produced/consumed tags mechanism (so as server, that would be a produced tag on the Logix device I think)
2. Explicit messaging - native tag addressing or if you map some things in Logix5000 I think you can use PCCC over EIP to get at tags mapped to data files.
If the robot supports EDS files you may be able to read a produced tag (likely an array of data to?) from the Logix controller - I know I could from the Schneider Ethernet/IP hardware using a particular EDS file. If you only want to read values perhaps that is enough. This is limited in functionality as there is no way to write values.
Forgot to add that you could write to tags in the AB PLC through the G3 - not quite as clean from an architecture standpoint, but you can use IO messaging to the G3 then have that use Native Tag Addressing or whatever to the AB PLC.