Control module MDD-1/T/420 1 input DEX...+ 4 output contacts, 4-20mA output, housing for TS35 rail.

Control module for gas detection systems – reliability and precision

The MDD-1/T/420 control module is a key element of the Digital Gas Detection System, designed to integrate threshold and measurement detectors with the RS-485 digital bus. It allows connecting one detector of the type DEX/F, DEX/A, DG/F, DG.EN or DEX/P, DG/P (with certain limitations regarding F6.., P6.., A6… models) and ensures reliable signal processing. This is an ideal solution for both professional installers and end-users who expect precise monitoring of gas concentration.

Functionality and flexibility in one device

The MDD-1/T/420 module offers a wide range of configuration options tailored to the specific needs of the installation. The ability to assign three alarm levels (A1, A2, A3) to a measurement detector and two levels for a threshold detector (A1, A2) allows for precise setting of warning thresholds. Additionally, the module enables calculating the weighted average NDS and NDSCh for toxic gases and selecting preferred measurement units – [%] of the measurement range, [%DGW], [ppm] or [%V/V]. Five available operating modes – “WITH MEMORY”, “WITH SUSTAIN”, “A3”, “WITHOUT MEMORY” and “SERVICE” – provide flexibility in managing the alarm system and adapting it to different usage scenarios.

Safety and communication

Safety is a priority in gas detection systems. The MDD-1/T/420 module has two 12V= alarm outputs for connecting acoustic and optical signaling devices and four relay outputs (galvanically isolated) for controlling fans, motors or building automation. An isolated RS-485 port (MODBUS RTU) enables easy integration with higher-level systems in the Digital Gas Detection System (e.g. with the MDD-256/T controller), where the module is treated as a “detector”. Additionally, the module is equipped with optical signaling of alarm and failure status and a built-in acoustic siren. It is worth mentioning the possibility of using an analog 4-20mA output (in the MDD-1/T/420 model) to control inverters.

Mounting and configuration

Mounting the module on a TS35 rail is quick and easy thanks to removable screwless terminals that accept both single- and multi-strand wires (without the need for ferrules). Configuration of settings is done using dedicated configuration software “DETnet View”, available on the manufacturer's website. The device remembers the last 200 events with start and end time and the source of the event, which facilitates analysis of system operation. Compact dimensions (106 x 90 x 65 mm) allow for installation in a limited space.