ABB RETA-02, User Manual

Page: 77 / 112

Communication
77
Requests and responses between the IO device and the IO
controller or the IO supervisor are transferred with the Record
Data Objects.
A write request is first sent containing the parameter request.
If the write request is valid, the RETA-02 acknowledges it with
request accepted. The master should then send a read request. If
the RETA-02 is still busy performing the internal parameter
request, it will return a negative response with the error code 0xB5
(State conflict). In this case, the read request will be repeated by
the master until the RETA-02 has the PROFIdrive response data
ready.
If the write request is invalid, a negative response is returned with
an error code.
Master Record Data Object Slave
Parameter
processing
Parameter request
Parameter response
PROFIdrive Write request
Write response
without data
Read request
without data
Read response (–)
without data
Read request
without data
Read response
with data
Parameter request
PROFIdrive
Parameter response