The different between ACE949 (first one reference) & ACE949-2 comes from distributed power supply level transmitted over each Sepam in parallel with RS485 Modbus line:
Last Revised: 29 Oct 2010 Original Author: EF Public All content © 1992-2010 Schneider Electric
ACE949 = 12V DC
ACE949-2 = 12V or 24V DC. With 24V DC level, the longer of distributed power supply line is increased.