ProSoft Technology MVI56E-MCMR MVI56E Modbus Master/Slave Enhanced Network Interface Module with Reduced Data Block for  ControlLogix processors, 1 x RJ45 Serial Configuration Port (CFG), 2 x RJ45 Communication Ports (Modbus), acts as an input/output module between the Modbus network and the ControlLogix backplane and allows  ControlLogix processors to interface easily with other Modbus compatible devices. Since the Reduced Data Block implementation requires less backplane/network bandwidth, the smaller data blocks are easier to schedule and transfer on ControlNet networks