Filter
Top Products
6 F 3 B 0 3 6 4
81
(6) How to Use the Semaphore Area
Figure 4.10 illustrates the usage of the areas and registers discussed at (1) to (5).
The squares in oblique lines in the figure indicate that "1" has been set to the flag registers and that
"256" has been set to the request register.
a) Use a READ instruction to the acknowledgement flag register to check for "0."
If a value other than "0" is found, write "0" in this area (first time only)
b) Use a WRITE instruction to write request data to the DN211 in the request area (top address:
0334H).
c) Use a WRITE instruction to write "1" in the request flag register.
d) Use a WRITE instruction to write "256" in the request register.
e) Use a READ instruction to read the acknowledgement flag register and waits until "1" is set to
the register.
f) Use a READ instruction to read response data of the DN211 from the acknowledgement area
when "1" is found in the acknowledgement flag register. (top address: 02DOH).
g) Use a WRITE instruction to write "0" in the acknowledgement flag register.
→ Returns to b).
T2/T2E/T2N
Writing in the
request area
Reading the
acknowledge-
ment area
Request flag
register
Requested
Reading the
acknowledgement
flag register
Completes
reading the
acknowledge
-ment area
Request
register
Request notification
Acknowl-
edgement
flag register
Completing reading
the request area
DN211
DN211
internal processing
Responded
Reading the
request
area
Writing in the
acknowledgment area
Figure 4.10 How to Use the Semaphore Area on Requests
(7) Cautions When Using the Semaphore Area
a) Since only a pair of request area and acknowledgment area is furnished, issue the next
request after the DN211 returns the acknowledgement to a request from the
T2/T2E/T2N.
b) Don't write data (no WRITE instruction) in the acknowledgement area /
acknowledgement flag register. Otherwise, data could be destroyed.
c) When a WRITE instruction writes data in the request area, be careful of the top
address and the data size to be written. Failing to do so could lead to the destruction of
other data, causing the DN211 to get malfunctioned.