Bosch Rexroth OptiFeed-FS EcoDrive 03 FLP04VRS, Functional Description

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ECODRIVE03-FL*-04VRS Command Communications
11-11
DOK-ECODR3-FL*-04VRS**-FK01-EN-P
Communication Between Master and Slave
A general description of the communication relationships is illustrated in
the following graphic. The following two services are shown from the
perspective of the master:
•
Read Request (Readout of the requested data)
(Readout of the response telegram)
•
Write Request (Read request)
(Write request)
Master Slave
Fieldbus
Read
Request
Read
Confirmation
Read
Response
Read
Indication
Fig. 11-17: Master Reads Datum
Master Slave
Fieldbus
Write
Request
Write
Confirmation
Write
Response
Write
Indication
Fig. 11-18: Master Writes Read or Write Request
The "Request" and "Indication" services contain the same data; the
difference is in the perspective ("Request’ from the master’s perspective,
"Indication" from the slave’s perspective).
If the master sends a service to the slave, the first word is the control
word. If, however, an answer is sent from the slave to the master, the first
word is the status word. Both words control the sequence of the Service
Data Channel.
If the data to be transmitted are longer than the length of the Service Data
Channel, they must be fragmented. The required information is also
contained in the control/status word. The total length that may be
transmitted via the Service Data Channel is 128 bytes.