A-811: High Performance Motion Control With EtherCat Connectivity

The A-811.CE single-axis motion controller from PI is an integrated electronics solution with a controller and servo drive in a compact desktop enclosure. The controller is intended for use with the PIglide air-bearing linear and rotation stages and other PI stages equipped with servomotors and high-resolution encoders.

  • Compact benchtop device, external AC/DC power supply
  • Complete-integrated servo-controller with drive
  • Encoder inputs support incremental (analog sine/cosine) and absolute (BiSS-C, EnDat 2.2) encoders
  • For voice coil drives, DC motors, and brushless 3-phase motors; quiet PWM drives
  • Output current up to 10 A continuous/20 A peak
  • Functional safety: STO (Safe Torque Off)

A-811.CED0x, dimensions in mm. Note that a comma is used in the drawings instead of a decimal point.

A-811.CED0x, dimensions in mm. Note that a comma is used in the drawings instead of a decimal point. Image Credit: PI (Physik Instrumente) LP

The typical controller has inputs for both incremental and absolute encoders. The integrated interpolation factor for sine/cosine encoders is up to 65536× (16 bit). The controllers encompass an onboard flash memory for stored motion programs and parameters.

The A-811.CE controller can be operated in a stand-alone mode using stored programs or from an external PC. Programming and initialization require a PC. The entire software package is included in the scope of delivery.

If the controller is purchased with a PIglide air-bearing stage or positioning system, PI will perform servo tuning, startup of the controller, and error calibration, resulting in a full ready-to-use positioning system.

The A-811.CE incorporates the cutting-edge ACS ECMsa Motion Controller with an incorporated servo drive.


  • Numerous motor current output levels


Source: PI (Physik Instrumente) LP



ACS ECMsa controller and servo drive, option of closed-loop servo-control, parameter change in operation.


Benchtop housing

Motor types

Brushless DC motors, brushed DC motors, voice coil motors

Number of drive axes


Motion and control A-811.CED0x

Controller type

Cascading PIVFF controller structure with loop-shaping filters, advanced feedforward, good disturbance repression, gain scheduling, field-oriented servo control, and space vector modulation

Sampling rate current control

20 kHz

Type of servo drive



Supported types:

Incremental: Analog 1 Vpp sine/cosine with index, differential, 4 x up to 65536x (16 Bit) interpolation, can be adjusted via software

Absolute: BiSS-C, EnDat 2.2

Max. velocity encoder impulses

Incremental: 500 kHz

Absolute: BiSS-C: 10 MHz, EnDat: 16 MHz

Limit switches

Incremental: 24 V DC, source or sink (preset on delivery); positive and negative limit switches; single-ended, opto-isolated

Absolute: n/a

Functional safety

STO (Safe Torque Off) input

SS1 (Safe Stop 1)

Interfaces and operation A-811.CED0x

Digital I/O lines

2 × input, 24 V DC sinking (1 × usable as a MARK position lock)

2 × output, 24 V DC sourcing or sinking (1 x usable as motor brake output)

Analog I/O lines

2 × input, differential, 16 bit

2 × output, differential, 10 bit

Output for position event generator (PEG)

1 × RS-422 differential, 5 V high-speed output for position trigger

Motor brake output

1 × 24 V DC, 1 A max. sourcing (connected with 2nd DOUT)

Communication interfaces

Ethernet: TCP/IP (100/1000 Mbps), EtherNet/IP

User software

ACS SPiiPlus MMI Application Studio (included in the scope of delivery)

Command set

ACS SPiiPlus ACSPL+ command set (included in the scope of delivery)

Application programming interfaces

Programming libraries for C/C++, COM, .NET (included in the scope of delivery)

Control rate and EtherCAT clock rate

2 kHz

Electrical properties A-811.CED0x

Output voltage

24 to 48 V, depending on the input voltage

Motor output current

A-811.CED02: 2.5 A continuous operation, 5 A peak

A-811.CED05: 5 A continuous operation, 10 A peak

Miscellaneous A-811.CED0x


Fan on the side (continuous operation, constant speed)


D-sub for motor and signal connections

Input voltage

24 to 48 V DC

Input current

A-811.CED02: 2 A continuous operation, 4 A peak for 2.5/5 A output current

A-811.CED05: 4 A continuous operation, 8 A peak for 5/10 A output current

Operating temperature range

5 °C to 40 °C


1.7 kg


180 mm × 270 mm × 74 mm (W × L × H)

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