Delta Tau ACC-24E2

Technical Specifications Model: ACC-24E2 2CH Manufacturer: Delta Tau Data Systems, Inc. Supported Axes: 2 simultaneous servo or stepper interface channels Output Command Types: PWM (digital) for servo drives; Pulse/Direction (PFM) for stepper drives Encoder Inputs: differential (RS-422) or single-ended (A/B/Z) per axis Encoder Interpolation: 4096× for 1 Vpp sinusoidal encoders (with appropriate option) SSI Encoder Interface: up to 8 channels (with option) Flag I/O per Channel: 8 input flags, 2 output flags Flag Input Voltage: 5 V to 24 V (selectable) Backplane Interface: UBUS / UMAC expansion bus Onboard Processor: none (dedicated interface module controlled by UMAC CPU) Servo IC: one highly integrated 4-channel PMAC2-style Servo IC Maximum Boards per UMAC: up to 8 ACC-24E2x boards (32 channels total) MACRO Station Support: 8-axis MACRO CPU supports 2 boards; 16-axis MACRO CPU supports 4 boards Operating Temperature: 0 to +45 °C (or -20 to +60 °C depending on configuration) Storage Temperature: -25 to +70 °C Humidity: 10% to 95% non-condensing Protection: IP20 Dimensions (without option): 16.256 cm length × 10 cm height × 2.03 cm width Connector: DB-15 female front-panel connector(s), option connectors per channel

Functional Features Two independent servo/stepper channels with per-channel configuration. Direct PWM output drives PWM-input servo amplifiers with configurable carrier frequency. PFM pulse/direction output drives stepper motor drives with programmable pulse rates. Differential or single-ended encoder input supports quadrature A/B/Z signals. 4096× interpolation for 1 Vpp sinusoidal encoders delivers high-resolution position feedback. Eight input flags and two output flags per channel support limit switches, home sensors, enable outputs, and fault signals. Encoder loss detection circuit monitors feedback integrity. Up to eight boards stack in one UMAC chassis for 32-axis systems.

Application Scenarios Multi-axis motion control in CNC machine tools, robotic arms, semiconductor manufacturing equipment, automated assembly machines, packaging lines, coordinate measuring machines, and scientific instrumentation. Used wherever the UMAC or MACRO Station controller requires additional digital servo or stepper axis interfaces beyond the base CPU configuration.

Performance Parameters Channels per board: 2 PWM resolution: 16-bit equivalent PFM maximum pulse rate: up to several MHz (configuration-dependent) Encoder input frequency: up to 15 MHz quadrature (differential) Flag inputs: 8 per channel, 5 to 24 V Flag outputs: 2 per channel, open-collector Update rate: synchronized to UMAC servo cycle (typically 10 to 100 µs) Expansion capacity: up to 8 boards per UMAC, 32 channels total

Material Composition FR-4 glass-epoxy PCB with solder-mask and silkscreen. Gold-plated backplane connector and DB-15 front-panel connectors. Aluminum front panel with silk-screened labels. Surface-mount integrated circuits including the PMAC2 Servo IC, line drivers, and optocouplers. Steel standoffs and mounting hardware.

Structural Features 3U Eurocard form-factor plug-in board for the UMAC rack. Front panel features one or two DB-15 female connectors for axis signals (encoder, PWM, flags), status LEDs, and a captive retaining screw. The board contains one 4-channel PMAC2-style Servo IC with buffering circuitry and connectors. Option modules (Option 1, etc.) can be piggybacked to add features such as SSI, 1 Vpp encoder input, or analog outputs. The rear connector mates with the UMAC backplane for power, UBUS communication, and inter-board signaling.

Working Principle The UMAC or MACRO Station CPU computes motion control algorithms (trajectory generation, PID/feedforward, phase compensation) and writes 16-bit command values to the ACC-24E2 over the UBUS backplane. The PMAC2 Servo IC on the board converts each command into either a PWM duty-cycle signal for servo amplifiers or a pulse/direction PFM stream for stepper drives. Encoder feedback from each axis is received, counted, and interpolated by the Servo IC, then read back by the CPU to close the position loop. Flag I/O signals are monitored and controlled through the same Servo IC registers. The board performs no independent processing; all intelligence resides in the host CPU.

Installation Requirements Power off the UMAC chassis before installing or removing the board. Insert the ACC-24E2 into an available 3U slot on the UMAC backplane and tighten the front-panel retaining screws. Connect axis cables to the DB-15 front-panel connectors using shielded cable. Configure each channel’s output mode (PWM or PFM), encoder type, and flag voltage through the UMAC configuration software. Verify that the total number of boards does not exceed the CPU’s axis capacity (2 boards for 8-axis MACRO CPU, 4 boards for 16-axis MACRO CPU, up to 8 for UMAC). Ensure ambient temperature stays within the rated range.

Usage Precautions Do not install or remove the board while power is applied. Connect encoder cables with correct pinout; reversed differential signals cause position-count errors. Use shielded cable for all encoder and motor command wiring and ground shields at the controller end. Set flag input voltage (5 V or 24 V) to match the connected sensors. Do not exceed the maximum encoder input frequency. Verify PWM polarity and enable signal logic before energizing servo drives to prevent unexpected motion. Keep motor power cables separate from encoder feedback cables to reduce EMI.