Toshiba 2000 V Series - Page 92

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model 2000 DeviceNet Module Manual (DN611/DN611A)
Chapter 4 Operating Procedures for the DN611 (Software)
4
Figure 4-15 How to Use the Semaphore Area on Requests
(7) Precautions in using the semaphore area
• Since only a pair of request area and acknowledgment area is available, issue the
next request after the DN611 returns the acknowledgement of a request from the
S controller.
• Don't write data (no MWRITE instruction) in the acknowledgement area/acknowl-
edgement flag register. Otherwise, data could be destroyed.(except (6)(g))
• When writing data in the request area using an MWRITE instruction, be careful of
the top address and the size of data to be written. Failing to do so could lead to
the destruction of the data in other areas, possibly causing the DN611 to malfunc-
tion.
S controller
Request area
write
Acknowledgement
area read
Requested Acknowledgement flag Completion of
register read acknowledgement
Request flag
register
area read
Request notice
Request
register
Completion of
request area read
Acknow ledgement
flag register
Responded
DN611
DN611
internal processing
Request area read Acknowledgment area write