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Core Technical Specifications
The 51304439-175 MC-TDIA12 digital input circuit board accepts twelve independent discrete signals from field devices and sensors. This board measures 140 millimeters in height, 100 millimeters in width, and 80 millimeters in depth, with a total weight of approximately 0.50 kilograms. Each input channel operates at 24 volts DC with a nominal current draw of 8 milliamperes. The board provides 1500 volts of galvanic isolation between the field inputs and the logic side circuitry.
| Parameter | Specification |
|---|---|
| Brand | Honeywell |
| Model | 51304439-175 MC-TDIA12 |
| Category | Digital Input Circuit Board |
| Dimensions (H x W x D) | 140 x 100 x 80 mm |
| Weight | 0.50 kg |
| Input Channels | 12 (sinking) |
| Input Voltage | 24V DC (nominal) |
| Input Current | 8 mA per channel |
| On-State Voltage Range | 15–30V DC |
| Off-State Voltage Range | 0–5V DC |
| Input Impedance | 3 kΩ |
| Response Time | 1.5 ms (on/off) |
| Logic Supply | 100 mA @ 5V DC |
| Field Supply | 24V DC (external) |
| Memory | 1 KB RAM, 512 bytes EEPROM |
| Isolation | 1500V (channel-to-bus) |
| Operating Temperature | 0 to 60 °C |
| Humidity | 5% to 95% RH |
| Standards | CE, UL 508, CSA |
Input Performance and Signal Conditioning
The 51304439-175 MC-TDIA12 detects on-state voltages from 15 to 30 volts DC with built-in hysteresis for reliable switching. It recognizes off-state signals between 0 and 5 volts DC as a valid low condition. The board filters electrical noise using a 1.5-millisecond debounce filter on every input channel. It includes LED indicators that display the real-time status of each input point. This circuit board also supports change-of-state detection to minimize processor polling overhead.
Physical Installation and Mounting
You can mount this board directly onto any standard Honeywell backplane using its modular form factor. Its front panel features a 37-pin D-sub connector for all field input terminations. The unit’s compact dimensions enable flexible placement within system cabinets. LED indicators show power presence and input activation for each channel. The board’s robust construction meets IP20 protection standards for indoor industrial environments.
Memory and Data Management
The 51304439-175 MC-TDIA12 stores input status data in 1 kilobyte of internal dual-port RAM. It retains configuration settings in 512 bytes of non-volatile EEPROM memory. This board maps each input channel to a specific bit address in the processor’s I/O table. It buffers time-stamped state changes for sequence-of-events recording. The unit also includes an input filtering configuration that you can adjust via software.
Power Distribution and Environmental Tolerance
This board draws a typical current of 100 milliamperes from the 5-volt DC backplane supply. It also requires a separate 24-volt DC field supply rated at 150 milliamperes for sensor power. The 51304439-175 MC-TDIA12 operates reliably across a temperature range of 0 to 60 degrees Celsius. It withstands humidity levels from 5% to 95% without condensation. The unit provides 1500 volts of isolation between the field inputs and the logic bus for safety.
Configuration and Diagnostic Functions
You can configure each input channel with programmable debounce settings from 0 to 15 milliseconds. The board supports both pulse-catch mode and change-of-state reporting for flexible applications. It provides open-wire detection through a built-in pull-up resistor network. The 51304439-175 MC-TDIA12 also includes a loopback test feature for verifying channel integrity. These diagnostic capabilities reduce troubleshooting time and improve overall system availability.