Kendriya . May 15, 2014:

I completely agree with Mr. Rippon´s suggestions, but since we don´t have any context it is difficult to say which is the right one. As far as the question is about a communication module, the first suggestion seems to make more sense.

In this sense, I was also wondering if 反 of 反対 is missing, i.e. 反対主制御部 通信 モジュール...Could it be something like "module that blocks the functions of/the information received from the main unit" (if we consider that 反対 means "adverse, anti-")... This is just another idea. I hope it will help.
Good luck:)

Julian Rippon May 15, 2014:

I have two ideas, depending on whether there are any additional characters before the 対.

1) If there are some characters before 対, let's say "XYZ".

Does 主制御部 appear elsewhere on its own, ie not as part of the longer term in question?
If so, then this is probably something like a "main control unit".

The overall term could then be something like:

XYZ 対 主制御部 通信 モジュール

ie "module for communications between XYZ and the main control unit"

2) On the other hand, if there are no characters XYZ, then it could just be

対 主制御部 通信 モジュール

ie "module for communicating with the main control unit"