The DP820 is a high-performance dual-channel pulse counting module designed for the ABB Ability™ System 800xA®, specifically engineered for precise measurement and control in industrial automation environments. This module is suitable for connecting incremental pulse transmitters and supports input frequencies up to 1.5 MHz, enabling high-precision simultaneous measurement of position, length, speed, and frequency. The DP820 offers strong signal compatibility, supporting various sensor signal interfaces such as RS422, +5V, +12V, +24V, and 13 mA. It is widely used in industrial applications including machinery control, motion monitoring, flow measurement, and speed feedback.
The module features a modular design and can be used with various termination units (such as TU810V1, TU812V1, TU814V1, TU830V1, TU833), offering flexible installation and strong adaptability. Each channel is equipped with independent counters, registers, and digital input/output interfaces, supporting bidirectional counting, frequency measurement, gated counting, and digital output control to meet the needs of complex industrial applications.
II. Key Features and Benefits
| Feature | Description |
| Dual Independent Channels | Two completely independent channels allow simultaneous pulse counting and frequency measurement without interference. |
| Multi-Signal Interface Compatibility | Supports RS422, +5V, +12V, +24V, and 13 mA sensor signals, adaptable to various industrial sensors. |
| High-Precision Counting & Measurement | 29-bit bidirectional counter (28-bit + sign bit). Frequency measurement range: 0.25 Hz – 1.5 MHz. |
| Flexible Pulse Encoding Modes | Supports Up/Down count mode, Count/Direction mode, and Quadrature encoder mode (x1, x2, x4 multiplication). |
| Gated Counting Function | Counting can be enabled/disabled via the Digital Input (DI), supporting both level-triggered and edge-triggered modes. |
| Configurable Digital Output | Supports various output modes including pulse output, level output, and coincidence-triggered output with configurable timing. |
| Powerful Synchronization & Sampling Functions | Supports user-defined synchronization conditions, sample conditions, and coincidence comparison for complex control logic. |
| High-Reliability Design | All channels are electrically isolated. Inputs feature overvoltage protection (up to 30 V). Supports Output Set as Predetermined (OSP) function. |
| Easy Integration & Maintenance | Compatible with various S800 system termination units. Features LED status indicators for easy field debugging and diagnostics. |
III. Functional Details
1. Transducer Connection
Each channel provides the following interfaces:
A, B, ST: Balanced inputs for pulse signals and synchronization signals.
DI: Digital Input for gating, synchronization, or external triggering.
DO: Digital Output, max load current 0.5 A, supports 24 V DC output.
All signals are electrically isolated. Inputs feature overvoltage protection and can withstand up to 30 V without damage.
2. Pulse Encoding Methods
The DP820 supports three pulse encoding methods:
Up/Down Count Mode: A pulses count up, B pulses count down.
Count/Direction Mode: A pulses are counted, B signal determines direction (B=0 down, B=1 up).
Quadrature Encoder Mode: Uses A and B phase-shifted signals. Supports x1, x2, x4 multiplication. Direction is determined by phase relationship.
3. Pulse Count (Length/Position) Measurement
Uses a 29-bit bidirectional counter for pulse accumulation.
Supports synchronization (reset to zero), sample freezing, and coincidence comparison functions.
Gated counting via the DI signal enables applications like length cutting and position locating.
4. Frequency (Speed) Measurement
Utilizes a dual-counter (SX, SR) method, calculating input frequency based on a reference frequency.
Measurement period can be controlled by a timer or the coincidence comparison function.
Supports synchronized measurement between channels for system coordination.
5. Digital Output Function
The digital output can be configured in four modes:
Coincidence-triggered pulse output (pulse width configurable).
Level-triggered pulse output (re-triggerable).
Direct level output.
Combination of coincidence and level control.
6. OSP (Output Set as Predetermined) Function
When the watchdog timer expires or a SetOSPState command is received, the outputs enter a predetermined safe state, enhancing system safety.
IV. Application Areas
The DP820 module is suitable for the following industrial scenarios:
Machinery Positioning Control: e.g., position feedback for machine tools, robots, conveyor lines.
Speed & Frequency Monitoring: e.g., motor speed, fan speed, pump frequency monitoring.
Flow Measurement: Counting and accumulation for pulse-type flow meters.
Length Measurement: Length measurement and cutting control for coiled materials, wires, etc.
Synchronization Control: Multi-axis motion synchronization, phase alignment.
Safety & Status Monitoring: Implementing safety interlocks or equipment status sampling via gated counting.
V. Installation and Wiring Instructions
The DP820 must be used with corresponding Module Termination Units (MTUs). Common combinations include:
TU810 / TU814: Compact termination units for general industrial environments.
TU812: D-Sub 25-pin connector for high-density wiring applications.
TU830 / TU833: Extended termination units supporting a wider range of signal types and external resistor configurations.
Wiring Notes:
Use shielded twisted pair cables with a characteristic impedance of 100 Ω (±25%).
12V/24V signals require external matching resistors (refer to technical drawings).
Input filters should be selected appropriately based on signal type and frequency.
VI. Status Indication and Diagnostics
The DP820 front panel provides multiple LED indicators for easy field status monitoring:
PX1/PX2: A/B Pulse Indicator (Yellow)
UP1/UP2: Count Direction Up Indicator (Yellow)
ST1/ST2: ST Pulse Indicator (Yellow)
DI1/DI2: DI Input Indicator (Yellow)
SY1/SY2: Counter Synchronization Indicator (Yellow)
DO1/DO2: Digital Output Active Indicator (Yellow)
TP1/TP2: Transducer Power OK Indicator (Green)
