Technical Specifications
- Supported Motion Axis Quantity: 24 fully independent servo/stepper axes
- Command Output Format: Differential step pulse + differential direction signal per axis
- Feedback Input Channels: 24 isolated digital fault/status input channels, sink/source jumper configurable
- Axis Enable Outputs: 24 solid-state relay isolated enable/disable control outputs
- Controller Communication Port: Dedicated differential multi-drop PMAC expansion bus
- Nominal Operating Supply Voltage: 24 VDC; allowable operating range 18 VDC – 30 VDC
- Full Load Power Consumption: Max 12 W under 24-axis simultaneous active operation
- Operating Ambient Temperature Range: 0 °C to +55 °C cabinet operational; -40 °C to +85 °C storage
- Channel Galvanic Isolation Rating: 2,500 VDC isolation between controller side and drive side per axis
- Maximum Step Pulse Output Frequency: 1 MHz per individual axis command channel
- Ingress Protection Grade: IP20 for standard enclosed control cabinet rack installation
Functional Features
- Full electrical isolation between PMAC low-voltage control logic and high-noise servo drive power circuits to eliminate ground loop burnout
- Independent differential step/direction signal generation for each of 24 axes with slew-rate signal shaping to reduce electromagnetic radiation
- Configurable sinking/sourcing digital fault input detection for universal compatibility with all industrial servo amplifier brands
- Hardware interlock logic that globally disables all axis drive outputs upon emergency stop input trigger
- Front panel individual LED status indicators for step pulse activity, direction state, drive fault, and axis enable status per axis
- Built-in surge suppression circuitry on all drive-side I/O terminals to absorb voltage transients from motor switching noise
- Jumper-selectable pull-up/pull-down resistors for matching external drive input impedance
Performance Parameters
- Maximum aggregate step pulse throughput across all axes: 24 million pulses per second
- Step signal propagation delay: ≤ 120 ns per axis output channel
- Isolation dielectric withstand voltage: 2,500 VDC continuous for 60 seconds per channel barrier
- Digital input response capture latency: ≤ 80 ns fault signal detection speed
- Rated MTBF: 520,000 operating hours at +25 °C nominal cabinet temperature
- Signal output drive capacity: 20 mA differential sourcing/sinking per command channel
- Global emergency stop reaction time: ≤ 0.5 ms full axis disable execution
Material Composition
- Main rack enclosure housing: UL94-V0 flame retardant black ABS plastic frame with steel internal reinforcement plate
- Main printed circuit board: High noise immunity FR4 industrial fiberglass laminate
- Isolation components: High-speed optocoupler galvanic isolation ICs for every axis signal path
- I/O terminal blocks: Nickel-plated copper screw terminals with captive wire clamps
- Front panel indicator hardware: High brightness long-life industrial LEDs
- DIN rail mounting hardware: Corrosion resistant spring steel mounting clip
- Surge protection components: Metal oxide varistors (MOV) and TVS transient suppression diodes
Structural Characteristics
- Standard 19-inch rack compatible modular unit, 4U rack height form factor
- Dual terminal block zones separated on front panel: controller bus wiring zone and 24-axis drive wiring zone
- Dedicated external emergency stop hard-wire terminal port isolated from control bus signals
- Internal PCB layout fully segregates low-voltage controller communication circuits and high-noise drive interface circuits via grounded shielding partitions
- Integrated ventilation slotted side panels for passive convection cooling
- Lockable terminal block wire ports to prevent loose wiring vibration failure during machine operation
- Standard 35 mm EN 60715 DIN rail mounting support for cabinet installation without full 19-inch rack
Working Principle
Low-speed differential communication frames carrying motion trajectory step and direction commands transmit from PMAC motion controller through dedicated multi-drop bus to the ACC28B-A-D internal logic processor. On-board FPGA distributes decoded motion commands to isolated signal drivers for each axis, generating shaped differential step/direction pulse signals routed to external servo/stepper amplifiers. All 24 drive units return fault, ready, and limit switch digital feedback signals into isolated input circuits on the module. Optocoupler isolation barriers block common-mode voltage noise generated by motor drive switching semiconductors, preventing noise-induced motion position drift or controller hardware damage. Axis enable solid-state relay outputs receive global interlock logic signals from emergency stop circuits to cut drive activation power instantly during safety trigger events. Front panel LEDs continuously mirror real-time signal states for on-site equipment troubleshooting without software access to the PMAC controller.
Core Advantages
- Centralized 24-axis signal isolation architecture reduces quantity of separate signal isolation modules in multi-axis automation systems
- Universal sink/source digital input configuration compatible with all mainstream industrial servo drive brands
- Hardwired hardware emergency stop interlock independent of controller software logic to meet machine safety standard requirements
- Integrated surge and transient suppression eliminates external signal conditioning terminal blocks
- Dual mounting options (19-inch rack / DIN rail) flexible for compact and large control cabinet layouts
- Individual per-axis visual LED status drastically shortens wiring and drive fault diagnostic downtime
Applicable Industries
Large gantry automation systems, multi-station automotive assembly test rigs, multi-spindle precision CNC production lines, automated aerospace composite layup equipment, semiconductor panel transfer multi-axis robots, large-format laser cutting and engraving machinery, automated warehouse sorting multi-axis handling equipment
Installation Requirements
- Mount module inside IP54 or higher sealed industrial control cabinet only; outdoor unenclosed installation prohibited
- When using DIN rail mounting, retain minimum 20 mm vertical airflow clearance above and below unit
- For 19-inch rack installation, secure all four rack mounting lugs with M6 steel machine bolts at uniform torque of 3 N·m
- Run shielded twisted pair differential cabling for PMAC controller communication bus wiring; terminate shield drain wire to cabinet single-point ground bar
- All drive-side step/direction feedback wiring must use twisted pair shielded cable with shield grounded only at the ACC28B-A-D module terminal side
- Connect unit protective earth terminal to cabinet PE grounding busbar with minimum 1.5 mm² cross-section copper wire
Usage Precautions
- Do not operate module when cabinet ambient temperature exceeds +55 °C; excess temperature causes optocoupler timing drift and signal output failure
- Disconnect 24 VDC main power supply before modifying axis wiring or input/output jumper configurations
- Emergency stop hard wiring must run as dedicated independent cable, bundled separately from all motion signal cables to avoid noise interference
- Mechanical vibration exceeding 10 g continuous acceleration will loosen terminal block wire connections; install anti-vibration rack mounting pads for high-vibration production environments
- Do not connect unisolated mains voltage signals directly to any axis I/O terminals; all input signals must operate within 0–24 VDC logic voltage range
- Annual inspection of terminal block screw torque mandatory to prevent thermal overheating from loose wire contacts
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