This BCD conversion module translates binary coded decimal signals for the PLC. It reads thumbwheel switches, digital encoders, and panel meters directly. You can install this unit into any Series 620 rack slot. The module eliminates manual data entry errors from operator panels.
Technical Specifications & Key Parameters
| Parameter | Detail |
|---|---|
| Product Model | Honeywell 621-0006 |
| Category | BCD Conversion Module |
| Dimensions (H x W x D) | 230 mm x 160 mm x 25 mm |
| Weight | 0.34 kg (0.75 lbs) |
| Number of Inputs | 16 BCD input points (4 digits, 4 bits per digit) |
| BCD Format | 8-4-2-1 binary coded decimal (positive logic) |
| Input Voltage Range | 24 V DC (10–30 V DC range) |
| Input Current | 7 mA typical at 24 V DC |
| Update Rate | 25 ms per scan (all digits updated simultaneously) |
| Component Count | 18 ICs, 24 capacitors, 32 resistors |
| Energy Storage | 220 µF capacitor (holds last BCD value for 10 ms) |
| Operating Voltage | 5V DC from backplane |
| Current Draw | 150 mA at 5V DC |
| Connector Type | Two 20-pin removable screw terminal blocks |
| Wire Size | 16–22 AWG copper stranded |
| Status LEDs | Power, input active (16 LEDs optional), fault |
| Input Protection | Opto-isolation (1500 V RMS) |
Detailed Feature Overview
Honeywell 621-0006 reads 16 BCD input points from thumbwheel switches. This configuration represents four decimal digits with four bits each. The module uses standard 8-4-2-1 positive logic BCD encoding. It converts each digit into a binary value for the PLC processor. Consequently, operators can enter setpoints and parameters without programming terminals.
All input channels update simultaneously every 25 milliseconds. This fast update captures rapid changes from digital encoders. Optical isolation at 1500 V RMS protects the PLC from field wiring surges. A 220 µF capacitor holds the last BCD value for 10 milliseconds during power dips. Therefore, momentary power interruptions do not corrupt operator entries.
Wiring and Configuration
Two removable terminal blocks accept 24 V DC signals from thumbwheel switches. Each digit requires four wires plus a common connection. The module supports common positive or common negative wiring. Eighteen integrated circuits decode the BCD inputs into PLC-readable format. Twenty-four capacitors filter noise on all input channels for reliable readings.
Installation and Environmental Requirements
This module draws only 150 mA from the 5V DC backplane supply. Its lightweight 0.34 kg design simplifies mounting in any rack slot. Two removable terminal blocks simplify wiring changes without removing the module. Use 16–22 AWG stranded copper wire for all field connections. Operating temperature ranges from 0°C to 60°C reliably. Keep humidity below 95% without condensation for long life. Store the module between -40°C and 85°C for long-term preservation.
Details
| Weight | 0.2 kg |
|---|---|
| Dimensions | 85 × 65 × 30 mm |
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