The MTT MS3759 Slim Plug-In Pulse to Relay Contact Converter takes dry contact, open collector, or wet contact input signals and converts them into clean relay contact outputs, giving control panels a reliable interface point between low-level field switching and equipment that expects a solid relay contact closure. It is available with either photo MOS FET (Form A) or mechanical relay (Form C) output stages, so it can be matched to applications that need fast solid-state switching or the wider voltage and current handling of a traditional mechanical relay.
Two independent, isolated outputs let one MS3759 drive two separate downstream circuits from a single field contact, which simplifies wiring in panels that need to fan a status or alarm signal out to more than one destination. A front-accessible switch lets technicians select between dry contact and wet contact sensing without opening the housing, while LED indicators for input state and relay activation make commissioning and troubleshooting straightforward. Four-way isolation between input, both outputs, power, and ground keeps the converter safely decoupled from noise and ground loops elsewhere in the system.
| Input Signal Types | Dry contact / open collector or wet contact (switch-selectable) |
| Dry Contact Pull-up | O1 code: ~13V, 3.3kΩ; O2 code: ~24V, 6.2kΩ |
| Wet Contact Levels | High 5-30V DC; Low 0-1V DC |
| Input Resistance | 1MΩ min. (with power); 10kΩ min. (without power) |
| Max Input Voltage | 30V DC continuous; threshold voltage ~2V |
| Max Frequency / Min Pulse Width | 1Hz max frequency; 30ms min. pulse width |
| Output Contact Types | Form A (Photo MOS FET) or Form C (mechanical relay) |
| Form A Ratings | 350V peak max; 120mA continuous; 50Ω max ON resistance; 1µA max off-state leakage |
| Form C Ratings | 250V AC / 220V DC; 2A max; 125VA / 30W max power |
| Response Time | 30ms max |
| Form C Life | 10⁶ cycles electrical life; 100×10⁶ cycles mechanical life |
| Isolation | 4-way isolation between input, Output 1, Output 2, power, and ground; 100MΩ min. insulation resistance; 2000V AC dielectric strength (input/output), 500V AC (between outputs) |
| Power Supply | 100-240V AC (85-264V AC, 47-63Hz), 24V DC ±10%, or 100-240V DC (85-264V DC); 4.5VA max (AC) / 1.5W max (24V DC) / 2.0W max (DC); 160mA fuse standard |
| Accuracy | Power sensitivity better than ±0.1% of span for each power supply range |
| Relay Startup Delay | ~2 seconds after power-up |
| Dimensions | W29 x H86 x D125mm (including mounting screw and socket) |
| Weight | 120g (main unit) / 80g (socket) max |
| Terminals | M3.5 screw terminals with protective cover, 0.8-1.0 Nm torque |
| Mounting | Wall or DIN rail mount |
| Operating Conditions | -5 to 55°C, 5-90% RH non-condensing |
| Storage Temperature | -10 to 60°C |
| Additional Features | LED indicators (green input setting, red relay activation), front-accessible input selection switch |
Frequently Asked Questions
What is the MTT MS3759 used for?
It’s a slim plug-in pulse to relay contact converter that takes dry contact, open collector, or wet contact input signals and converts them into clean relay contact outputs, giving control panels a reliable interface point between low-level field switching and equipment that expects a solid relay contact closure.
What’s the difference between the Form A and Form C output options?
Form A uses a photo MOS FET for fast, solid-state switching (350V peak max, 120mA continuous, no moving parts), while Form C uses a mechanical relay for wider voltage and current handling. Choose Form A for frequent switching or long service life, and Form C where you need to switch higher power directly.
What input signal types does it accept?
Dry contact, open collector, or wet contact, switch-selectable on the unit. Wet contact levels are 5-30V DC for high and 0-1V DC for low. Tell us which type your field switch or sensor outputs and we can confirm the setup.
What’s the maximum switching speed?
1Hz max frequency with a 30ms minimum pulse width, suited to slower contact-closure signals like limit switches or counters rather than high-speed pulse trains.
How do I know if the MS3759 is right for my application?
If you need to convert a low-level dry contact, open collector, or wet contact signal into a standard relay contact output for your panel, the MS3759 is built for that. Send us your input signal type and the voltage/current your output side needs to switch, and we can confirm before you order.
Download MTT MS3759 Slim Plug-In Pulse to Relay Contact Converter information here
Spec Sheet: MTT_SpecSheet1_MS3759_Rev150_E
Manual: MTT_Manual1_MS3759_Rev140_E
