Three controller products have been offered since the introduction and various stages of enhancement of the MOD 300 system.
The Model B controller (6000 Series) was the first controller introduced for MOD 300. It consisted of a single subsystem with up to three linked card files, each capable of supporting 4 controller modules. The subsystem was a single connection on the redundant DCN. The Local I/O was redundant and the controller redundancy was N:1 with N = 1 to 11.
In 1988 the SC-Controller (6200 Series) was Introduced with a updated microprocessor and both local redundant I/O and Taylor Remote I/O (TRIO). In addition the Taylor Ladder Logic (TLL) control language was added.
In 1992, the AC400 controller series was introduced. The AC460 provided increased memory capacity, processor speeds, and an improved redundancy scheme. The AC410 provided similar control functionality for smaller, non-redundant applications.