Multi-axis servo drive
ACS Motion Control SPiiPlus MC4U multi-axis servo drive
Rack-style control module combining a 2–64 axis EtherCAT controller with up to 8 integrated drive axes, 85–400 V AC input, up to 45/90 A per axis (4 axes) and 9 to 22 inch enclosure widths.
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What are you specifying?
Select everything you need. A motor, drive and gearbox can be specified together as one axis.
Key specifications
| Data / bus | EtherCAT, EtherNet/IP, Modbus |
|---|---|
| Supply | 85–400 V AC (bus 24–320 V DC by supply module) |
| Feedback | up to 8 encoder channels (AqB, SinCos, absolute) |
| Fieldbus | EtherCAT MainDevice or SubDevice, up to 5 kHz |
| Axes | 8 |
| Continuous current (max) | 45 A |
| Peak current (max) | 90 A |
| Safe torque off | STO option |
Summarised in our own words from PI Group (Physik Instrumente)'s published data; series maxima, individual models vary. Last checked 2026-10-30. Source 1
Notes on this data
ACS lists current as 45/90 A (up to 4 axes) and 20/40 A (up to 8 axes) without labelling continuous/peak; interpreted as continuous/peak.
Specify Motion is not affiliated with PI Group (Physik Instrumente). ACS Motion Control and SPiiPlus MC4U are used only to identify the product. Comparisons use published figures; always confirm against the current datasheet.
ACS Motion Control SPiiPlus MC4U replacement and alternative options
Use these supply-network options as a starting point for an engineering check. We can also help source the original ACS Motion Control part. Published series figures do not establish an exact-model or drop-in replacement: confirm ratings, fit, interfaces and approvals for your application.
AMC's analogue servo drives for centralised control schemes: set up with DIP switches and potentiometers, commanded by +/-10 V or PWM. They span 10-400 VDC and 45-265 VAC, up to 150 A continuous and 250 A peak, in PCB, panel and vehicle formats. PCB extended-environment parts run -40 to +85 C.
| Published maximum | SPiiPlus MC4U | AxCent Analogue Servo Drives (AB, AZ, … |
|---|---|---|
| Continuous current | 45 A | 150 A meets or exceeds |
| Peak current | 90 A | 250 A meets or exceeds |
| Axes | 8 | — |
Network-capable AMC digital drives spanning 10-747 VDC and 120-480 VAC, up to 150 A continuous and 250 A peak (27.4 kW peak power), in PCB, panel, machine and vehicle formats. They support almost any motor type and feedback, plus CANopen, EtherCAT, POWERLINK and Modbus.
| Published maximum | SPiiPlus MC4U | DigiFlex Performance Servo Drives (DP,… |
|---|---|---|
| Continuous current | 45 A | 150 A meets or exceeds |
| Peak current | 90 A | 250 A meets or exceeds |
| Power | — | 27,400 W |
| Axes | 8 | — |
ADVANCED Motion Controls' ultra-compact, high power-density digital servo drives for 10-90 VDC systems, up to 100 A continuous and 200 A peak. They come in PCB, machine-embedded, panel and development-board formats, carry STO as standard, and run EtherCAT, CANopen or Ethernet/IP. Extended-environment models are rated -40 to +95 C.
| Published maximum | SPiiPlus MC4U | FlexPro Digital Servo Drives (FE, FX, … |
|---|---|---|
| Continuous current | 45 A | 100 A meets or exceeds |
| Peak current | 90 A | 200 A meets or exceeds |
| Axes | 8 | — |
Figures are the highest published for each series and are not always measured the same way. A higher figure is not automatically a better choice: mounting, duty cycle, feedback, connectors and approvals matter too. An engineer will check the fit against your application before recommending anything.
Typical applications
What a multi-axis servo drive is
A multi-axis servo drive controls two or more servo motors from one unit, usually sharing a power supply, DC bus and communication interface. Formats include compact two- to four-axis drives in one housing and modular systems with a common supply module and separate axis modules. Sharing the bus lets energy from a decelerating axis be used by others, reducing braking losses. Most connect to a motion controller or PLC over EtherCAT or another industrial Ethernet network.
When engineers choose a multi-axis servo drive
Choose a multi-axis drive for machines with several coordinated servo axes in one cabinet, such as robots, packaging machines and gantries. It saves space, wiring and cost per axis compared with single drives. The trade-offs are flexibility and fault isolation: axes share the supply, so a supply fault affects all axes, and replacing one module may need specific spare strategy. Mixing very different power levels can be limited by module ranges.
How to specify the ACS Motion Control SPiiPlus MC4U
Send these with your enquiry and an engineer can confirm the right SPiiPlus MC4U variant or an equivalent:
- Number of axes and power per axis (A, kW)
- Supply voltage (V AC or DC)
- Network interface and cycle time
- Motor and feedback types
- Shared bus and regenerative energy handling
- Safety functions per axis
- Cabinet size and cooling
Common mistakes to avoid
- Sizing supply module for the sum of peaks without considering simultaneous demand
- Ignoring how one fault affects all axes
- Choosing modules without room for future axes
- Overlooking network cycle time with many axes
ACS Motion Control SPiiPlus MC4U: frequently asked questions
Can you help replace ACS Motion Control SPiiPlus MC4U or source the original?
Send the full model code, quantity and required date. Our engineers can check original-part availability and assess suitable alternatives, including supply-network options where appropriate. We confirm compatibility and any changes needed before recommending a replacement.
What is the ACS Motion Control SPiiPlus MC4U?
Rack-style control module combining a 2–64 axis EtherCAT controller with up to 8 integrated drive axes, 85–400 V AC input, up to 45/90 A per axis (4 axes) and 9 to 22 inch enclosure widths. Published series figures include axes 8, continuous current 45 A, peak current 90 A. It is made by PI Group (Physik Instrumente); Specify Motion can help source it or propose an equivalent.
Who makes the ACS Motion Control SPiiPlus MC4U?
The ACS Motion Control SPiiPlus MC4U is made by ACS Motion Control (PI Group (Physik Instrumente)) and is listed here for engineers comparing options. Specify Motion is not affiliated with PI Group (Physik Instrumente); brand names are used only to identify the product.
What is the axes of the ACS Motion Control SPiiPlus MC4U?
The published series maximum axes is 8. Individual models and sizes in the SPiiPlus MC4U range vary, so check the exact variant against your duty cycle, mounting and environment, or ask our engineers to confirm the right size for you.
Is there an alternative to the ACS Motion Control SPiiPlus MC4U?
We can assess suitable replacement options. On published figures, ADVANCED Motion Controls AxCent Analogue Servo Drives (AB, AZ, AV, B, AVB) and ADVANCED Motion Controls DigiFlex Performance Servo Drives (DP, DZ, DV) are options to assess from our supply network. An engineer confirms the fit against your application before recommending anything.
What are the benefits of a shared DC bus?
On a shared DC bus, energy regenerated by a decelerating axis can be used by other axes that are accelerating, reducing the energy dissipated in braking resistors. It also reduces wiring and supply components. Sizing must consider simultaneous peak demand on the shared supply.
Are multi-axis drives cheaper than single-axis drives?
Typically, per axis, multi-axis drives cost less and take less cabinet space, because the supply, communication and housing are shared. The saving grows with the number of axes. For machines with only one or two axes, or widely separated axes, single drives can be simpler.
Further reading: How to select a multi axis servo drive · How to select a servo drive · Servo drives
Other multi-axis servo drive series
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