Discrete Mixed Modules | GE Fanuc Emerson IC200MDD843B

The IC200MDD843B is a high-density discrete mixed I/O module manufactured by GE Fanuc (now Emerson Automation Solutions) for the VersaMax I/O and control platform. Designed to save backplane rack space in compact control architectures, this revision B module combines 10 discrete input points (positive logic/sourcing) and 6 electromechanical relay output points into a single 16-point form factor. It plugs into standard VersaMax snap-on I/O carriers and derives logic power directly from the backplane.

Input/Output Circuitry and Electrical Characteristics

The module splits its 16 I/O points into two distinct circuit groups. The 10 discrete input points operate on positive logic (sourcing) field signals with a maximum signal response speed of 10 ms. The 6 output channels consist of moving-armature electromechanical relays with silver alloy contacts capable of switching up to 8 A total output current (maximum 20 cycles per minute under inductive load conditions). Field wiring connects via an 18-terminal Type A interface or a Type B terminal accessible through a shorting bar.

Power Distribution and Environmental Protection

Logic power for the module is drawn directly from the VersaMax rack-mounted backplane, consuming up to 190 mA depending on the total number of active inputs and energized relay coils. High-power field loads require an external DC or AC power supply.

Wiring and Load Protection Guidelines

Because the IC200MDD843B does not incorporate internal fuses, RC snubbers, or channel-to-channel isolation, system designers must adhere to standard field installation rules:

1. Install External Fusing: Wire external fast-acting fuses inline with each relay output circuit to protect module contacts against overcurrent and short circuits.
2. Add Inductive Suppression: Connect external suppression diodes across DC inductive loads or MOV/RC networks across AC inductive loads to prevent arcing across silver alloy contacts.

Frequently Asked Questions

Q: Does the IC200MDD843B module contain internal fuses to protect the 6 relay outputs?

A: No, the module lacks internal fuses or snubbers, so external fuses must be installed inline on the output field wiring.

Q: What is the maximum response time for input signal transitions on this module?

A: The input channels feature a maximum response speed of 10 ms for signal processing across the backplane.

Q: How does the IC200MDD843B receive operating power for its internal logic?

A: Primary logic power is drawn from the VersaMax rack backplane (up to 190 mA), while output load currents require a separate external power supply.