Designed and manufactured by the company known as Allen Bradley / Rockwell Automation, part number 1771-DCM is a direct communication module. This module can be mounted to a chassis, and it only takes up a single slot. This module was designed to allow for communication between a supervisory processor and local processors. The Allen Bradley 1771-DCM direct communication module can be used to transfer data table words, obtain predictable transfer times, and can decrease data highway traffic, as well as many other things. This direct communication module has a discrete data transfer rating of up to seven (7) words plus one (1) status word. Additionally, the block transfer rating of this module is up to sixty-three (63) words plus one (1) status word. The Allen Bradley 1771-DCM direct communication module has a communication/transmission rate of 57.6K baud or 115.2K baud. The response time of this module is less than fifteen (15) milliseconds. The interconnect cable that is compatible with this module is the 1770-DC. This cable should be a Belden 9463 cable or an equivalent. The backplane current rating of the Allen Bradley 1771-DCM direct communication module is 1.2 amperes.

The Allen Bradley 1771-DCM direct communication module should be operated within an environment where the temperature ranges from 0 to 60 degrees Celsius, or the equivalent temperature range of 32 to 140 degrees Fahrenheit. However, when this module is not being operated, or is being stored, the temperature of the surrounding environment should range from -40 to 85 degrees Celsius, or -40 to 185 degrees Fahrenheit. The relative humidity levels suitable for this module range from 5% to 95% with no condensation.