Yes. As of firmware version 3.00-00-42 the 'A' or 'B' designation can be selected by using the LCD panel.
The setting can be found by navigating to the PLC Operations / Hot Standby..
*** Previous to firmware version 3.0 the 'A' and 'B' designation was determined by the MAC address found on the lower front of the PLC.
With both PLCs on-line, the lowest MAC address was designated the "A" unit.
Legacy KB System (APS) Data: RESL207391 V1.0, Originally authored by DaSo on 02/14/2012, Last Edited by DaSo on 02/14/2012
Related ranges: Modicon Quantum