MDD-1/T/420

MDD-1/T digital measuring executive units are designed to connect one DEX/F, DEX/A, DG/F, DG.EN type threshold detector or one DEX/P, DG/P type measuring detector to the RS-485 industrial standard digital bus with MODBUS RTU protocol.

Features and functions performed

• assigns three alarm levels to the measuring detector: A1, A2 and A3, set by the user to any value within the full measurement range;
• assigns two alarm levels A1 and A2 to the threshold detector (according to the detector’s factory settings);
• allows calculation of the PEL with TWA and average STEL for detectors measuring toxic gas concentrations;
• allows to determine the type of displayed measurement units of the detector: [%] of the measuring range, [%LEL], [ppm] or [%V/V];
• enables five modes of operation: „WITH MEMORY” – signals the occurrence of alarms after their disappearance, „UPHOLDING” – sustains active alarm states after the alarm source has disappeared, „A3 MODE” – turns off the power supply to the detector with catalytic sensor, which protects against overload, „WITHOUT MEMORY” – will automatically reset the input and output states on the front panel after the alarm states disappear, „SERVICE” – deactivates unit’s outputs for 1 hour;
• visually indicates the signal value, the alarm and emergency states of the detector (LED display), the states of the control outputs A1, A2, A3 and the detector’s failure (LEDs);
• built-in siren;
• memorizes in a non-volatile internal memory the last 200 events with the assigned start and end times and source of the event;
• enables very precise determination of alarm delay times and the invariability of these parameters over time thanks to microprocessor control;
• two 12VDC alarm outputs (one for each A1 and A2 threshold) control additional acoustic and optical sirens;
• relay outputs (galvanically separated, one for each A1, A2, A3 and failure) control fans, motors, contactors, information boards, or connect to building/plant automation;
• isolated port in RS-485 standard (MODBUS RTU);
• in the Digital Gas Detection System (with MDD-256/T type master controller) the connection unit is treated as a „detector”;
• removable, screwless terminals, possibility of using wires with single or multi-stranded conductors (wires, without crimping sleeves) – quick installation, easy maintenance;
• mounting on TS35 rail;
• optional: isolated 4-20mA active analog output (model MDD-1/T/420) or 2-10V (model MDD-1/T/V10) provides control of inverters;
• configuration of unit’s settings via the dedicated „DETnet View” configuration software, available at https://www.gazex.pl/en/software/.