Pulse/Quadrature Input Module

The Logic Manager Special Function I/O Modules provide a variety of control and
communications functions for the Logic Manager I/O System. The special function
modules use the I/O bus for data transfer with the Logic Manager processor and rely on
PUSH/PULL instructions for communications. The PUSH/PULL interface allows these
modules to send or receive up to eight 16-bit registers of data at one time.

The 'R' suffix associated with most 621 model numbers indicates the module can be removed from or inserted into an I/O rack while the rack remains powered. Other I/O modules in the rack continue to control the machine or process.