Description
Product Introduction
The Delta Tau ACC-24E2 2CH is a specialized 2-axis interface expansion board engineered for the UMAC (Universal Motion and Automation Controller) system architecture. It bridges high-speed PMAC2 DSP processing cores to physical servo drives, linear motors, and feedback hardware. The card delivers precise ±10V analog velocity/torque command signals while simultaneously processing high-frequency quadrature encoder inputs.
Unlike standard PLC motion cards that suffer from slow backplane scan times, the ACC-24E2 2CH routes position feedback directly to the PMAC2 motion IC via a dedicated local bus. This enables sub-millisecond servo update rates, digital filter loop execution, and micro-positioning accuracy necessary for ultra-high precision CNC machinery, semiconductor wafer stages, and multi-axis gantry systems.
Key Technical Specifications
| Parameter | Value |
| Compatible Controller Base | UMAC (3U Eurocard form factor) / Turbo PMAC2 |
| Axis Capacity | 2 Independent Channels (2-Axis Servo Command) |
| Command Outputs | 2x Differential Analog Outputs (\pm 10V, 16-bit DAC resolution) |
| Encoder Inputs | 2x Differential Quadrature Encoder Channels (A, B, Index signals) |
| Maximum Encoder Frequency | Up to 10 MHz line driver inputs |
| Dedicated Axis Flags (Per Axis) | Home Switch, Positive Limit (+LMT), Negative Limit (-LMT), User Flag |
| Drive Interface Signals | Amplifier Enable (AEN), Fault/Alarm inputs per channel |
| Form Factor | 3U Eurocard format, slot-mounted into UMAC rack backplane |
| Power Consumption | +5V DC (\pm 5\%), \pm 12V or \pm 15V supplied via backplane |
| Operating Temperature | 0°C to +55°C (32°F to 131°F) |
ACC-24E2 2CH
ACC-24E2 2CH
Application Scenarios & The “Trench” Experience
Few things put a high-precision manufacturing line on hold like a blown DAC channel on a motion card during a production run. Consider a semiconductor wafer dicing rig or a precision 5-axis CNC diamond turning lathe: a sudden power spike on an enable line pops an operational amplifier on the axis card, leaving the PMAC rack throwing runaway position errors (Ixx11 faults). Trying to adapt a non-native motion controller requires rewriting complex PMAC trajectory routines, re-tuning servo algorithms, and setting up coordinate system transforms from scratch. Replacing the faulty ACC-24E2 2CH restores hardware-level servo synchronization immediately, keeping tuned PID filters intact and returning the tool head to sub-micron repeatability.
- Semiconductor Fabrication – Driving precision XY air-bearing wafer positioning stages requiring ultra-low jitter analog commands.
- Precision CNC & EDM – Interfacing linear motors and high-resolution glass scales on high-speed wire EDM cutting machines.
- Optical & Laser Alignment – Controlling multi-axis mirror mounts and beam-steering galvos in photonics research labs.
- Robotics & Test Benches – Providing closed-loop servo feedback and control for high-speed material handling rigs and flight simulators.
Transparency SOP: Quality Assurance & Testing
We don’t just ship boxes; we test them on actual Delta Tau UMAC chassis. Every surplus or refurbished ACC-24E2 2CH undergoes a strict 5-stage verification process before shipping:
- Inbound Physical Inspection: Inspection of 3U Eurocard edge connectors, front-panel DB15/terminal blocks, checking for thermal stressing, trace corrosion, or bent pins.
- UMAC Backplane Power-On Diagnostic: Mounted into a live UMAC rack; verified voltage drop across onboard logic regulators and checked for clean clock enumeration.
- Encoder Counter & Line Driver Test: Differential pulse signals injected at 1 MHz, 5 MHz, and 8 MHz across both channel encoder inputs; verified clean quadrature counting and zero lost counts in PEWIN32 / Executive software.
- Analog Command DAC Linearity Check: Step voltages (\pm 1V, \pm 5V, \pm 10V) commanded via software to check 16-bit DAC output calibration, ripple noise, and offset drift on an oscilloscope.
- Machine Flag & Enable I/O Validation: Physical triggering of Limit+, Limit-, Home, and Amplifier Enable (AEN) logic circuits to confirm optical isolation and register switching state.
The Veteran’s Tech Trap Guide (Crucial Value-Add)
⚠️ Check Jumpers for 4-Axis vs 2-Axis Base Board Configuration: The ACC-24E2 can exist in 2-channel (2CH) or 4-channel (4CH) variants. If you are dropping a 2CH board into a slot previously occupied by a 4CH card, verify that your PMAC variable settings (specifically Ixx05 memory mapping for motor channels) match the physical IC populations on the card. Otherwise, channels 3 and 4 will map to non-existent registers and trigger servo faults.
❗ Watch the Encoder Supply Voltage Jumpers: Delta Tau boards feature onboard jumper options (E-points) to select between 5V DC and 12V DC power for connected encoder optics. Always measure the voltage across the encoder power pins before plugging in your feedback cable. Supplying 12V to a 5V glass scale encoder will burn out the scale head instantly.
⚠️ Differential vs. Single-Ended Signals: The ACC-24E2 expects differential RS-422 line-driver encoder signals (A+, A-, B+, B-, Index+, Index-). If you are connecting old single-ended (open-collector) encoders, you must use signal converter boards or bridge the negative differential inputs correctly, or noise spikes will cause erratic position drift.
❗ DAC Voltage Drift & Offset Calibration: Over years of thermal cycling, operational amplifiers on legacy analog cards can develop slight DC offsets (e.g., 50mV instead of 0V at rest). Before dropping a replacement card into a closed-loop system, run a DAC zero-offset command in PMAC (using Ixx09 DAC bias adjustment) so the drive doesn’t jump when the main loop enables.
Frequently Asked Questions (FAQ for Conversion)
Q: What is the main difference between an ACC-24E2 2CH and an ACC-24E2 4CH?
A: The ACC-24E2 2CH only populates the onboard DSP channels, DACs, and connectors required to run 2 axes, whereas the 4CH version is fully populated for 4 axes. If your machine only uses 2 axes on that expansion slot, the 2CH version is a cost-effective 1:1 drop-in replacement.
Q: Can I use this card with a Turbo PMAC2 UMAC CPU?
A: Yes. The ACC-24E2 series is natively designed to interface via the 3U Eurocard UMAC expansion backplane and communicates directly with Turbo PMAC2 and Power PMAC UMAC CPU modules.
Q: Do I need special software to configure the ACC-24E2 2CH?
A: Configuration is performed via standard Delta Tau engineering tools, such as PEWIN32 PRO (for Turbo PMAC) or Power PMAC IDE. Register setup involves configuring motor I/O pointers to recognize the board’s physical base address on the UMAC bus.
Q: Is the ACC-24E2 2CH hot-swappable in a UMAC rack?
A: Absolutely not. Inserting or removing any 3U Eurocard module while the UMAC power supply is turned on will damage the backplane bus drivers and fry the DSP chip on the main CPU board. Always shut down main 24V/5V system power before pulling the card.
Q: What warranty comes with this replacement card?
A: All our new surplus and bench-tested refurbished Delta Tau cards come backed by a full 12-month direct replacement warranty. If a board fails under normal operating conditions within one year, we will swap it out immediately from our stock.
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