How to Control BissC Absolute Encoder in EtherCAT Motion Controller

What is Bissc Absolute Encoder?

BissC means Binary Synchronous Serial Communication . From the name, it can be known it is one digital interface protocol . Moreover, it is one communication protocol for data transferring between motion control and absolute encoder. And one main feature is "master-slave" interface because it uses fast dual-station synchronous serial interface mode.

In BissC protocol, master interface controls the sequence of position capture and data transferring speed, then encoder as the slave interface, mainly to respond main interface's position capture request.

BISS Interface

BissC Absolute Grating Ruler

must meet below requirements:

*Controller Model: ZMC432-V2, ZMC406-V2

*Firmware Version: above 4.930-20190305

*AXIS Interface: for ZMC432-V2 series, only AXIS4/5 support SSI/BISS communication.

You can check through "controller status", if there is "Ssi", which means it supports.

: PLC / Basic / HMI.

--PC Languages: C#, C++, LabVIEW, Matlab, Qt, Linux, VB.Net, Python

ZMC432-V2 AXIS4/5 SSI/BISS

(3) Needed Parameters

--ATYPE: Axis Type--

48 = SSI absolute encoder, 49 = BISS absolute encoder

--UNITS: Pulse Amount--

Take BissC absolute grating ruler as the example, resolution is 100nm, then one pulse corresponds to 100nm, 1mm = 10000 pulses, that is, controller sets this axis' UNITS according to this parameter.

--ENCODER_BITS: SSI/BISS Encoder Absolute Bit--

Refer to BissC absolute encoder manual data bit. Some BissC absolute encoders have more auxiliary state bits, generally there are 18-20 bits. ENCODER_BITS can manually adjust it. ENOCDER_BITS = data bit + auxiliary state bit (some encoders don't support).

--General Rotary Absolute Encoder--

Use signal to set origin position.

--Others--

Please contact with encoder manufacturers.

(6) Absolute Encoder Position Reading

A. How to Achieve

Step 1: clear encoder position at origin position.

Step 2: set UNITS

Step 3: read axis 4 / axis 5 MPOS value to get encoder current position, if you need encoder original value, read axis 4 / axis 5 ENCODER.

Note: BissC absolute encoder position supports power failure storage.

B. Example:

Manually rotate BissC absolute encoder, and capture the position curve by oscilloscope, then you will get: