Siemens LMV3 series, Технические инструкции

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Technical Instructions LMV Series
Document No. LV3-1000
Section 7 Page 4 SCC Inc.
Temporal process of a data inquiry
Time scheme
A data inquiry progresses according to the following scheme:
where:
t0 Identification code for the end = 3.5 characters
(time is dependent on the Baud rate)
t1 Dependent on the time required for internal handling.
The maximum handling time is dependent on the number of data.
In case of read access for 6 parameters: 50 ms
In case of write access for 2 parameters: 50 ms
t2
t2
≥
50 ms
This is the time required by the device to switch back from sending to
receiving. It must be observed by the master before making a new data
inquiry. It must always be observed, even if the new data inquiry is made to
some other device.
Communication during the internal slave handling time
During the slave’s internal handling time, the master must not make any data inquiries. Any inquiries
made during this period of time will be ignored by the slave.
Communication during the slave’s response time
During the time the slave responds, the master must not make any data inquiries. If inquiries are made
during this period of time, all data currently on the bus become invalid.
Number of addresses per message
The number of addresses per message is limited:
•
20 addresses the size of a word when reading
•
6 addresses the size of a word when writing
•
For fault history, messages must be exactly 8 or 16 addresses