The thumbwheel interface module supplies the 24 VDC power for the thumbwheel swithches. It is recommended that you provide a diode to isolate each signal line. This is a standard option with most thumbwheels. The thumbwheels must be BCD coded. Newark lists thumbwheels from several manufacturers.
The data from each of four thumbwheels is written to the presets for timer or counter register 674 through 677.
The thumbwheel interface module must be located in slots 2 through 5 of the same base that houses the CPU module.