Reading Position Data from AS33-M42M Encoder

[Jooje]

Hi friends,


I'm trying to read data from my Broadcom AS33-M42M absolute encoder. According to the datasheet, it uses RS-485 as the physical layer, but I couldn't find any details about the communication protocol or the command structure required to request data from the encoder. There are no clear instructions on what commands I need to send or how the data is structured in the response.

Does anyone have experience with this encoder or know where I can find the RS-485 protocol details? Is there a separate RS-485 software specification document from Broadcom that provides the necessary information? Any guidance or sample commands would be greatly appreciated!


Thanks in advance!

 

[doraemon]

Hello!

You can find detail of BiSS protocol at this link.

BiSS Association e.V. - BiSS Interface

BiSS User Society and Internet Platform BiSS Interface Open Source Sensor/Actuator Interface Bus capability Safety capability BiSS Line Protocol - Full BiSS C compatibility for One-Cable Technologies More than 650 companies worldwide trust in BiSS. Get your free BiSS license today and benefit...

biss-interface.com

You can download the full protocol description and application notes.
It's also possible to bit-bang it, and just in case, I think TI has some CPUs
with BiSS interface integrated. At least I heard about it, and possibly also
Renesas, not sure.

Among the merits of BiSS protocol:
- Duplex connection: you can send command without interrupting the data flow as you would
do with, for example, SPI. You can have register communication while you are sending data.
- 10 MHz
- No waste of data bits. If you need 18 bit, then you transmit 18, not 24 bits as you would
do with other physical layers.
- Integrated error / warning mechanism
- Possibility of chaining sensors serially. In this case, all data of all sensors are latched
at the first master clock rising edge.
- Data with CRC.
- Electronic datasheet.

This latter feature is quite interesting. The BiSS master can sniff out what the sensor can do
and configure itself accordingly.


Dora

 

[FvM]

Different version of the encoder are using different protocols. You need to look at the full part number, -B is BISS, -S SSI and -K RS485. RS485 protocol details are not in the datasheet, there should be an additional manufacturer spec.

 

[KlausST]

Hi,

You provided the datasheet
Did you read it?

It clearly says:

Refer to the AS33-M42M RS485 software specification document for detailed information.

--> ask the manufacturer for this document.

Klaus