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5.2.1 Accessing the DN211 in Module Setting
This section describes how to access the DN211 in module setting. The semaphore area of the
DN211 is used for this accessing. It is the area used for issuing requests from the T2/T2E/T2N for
operating the DN211 or reading the response to a request from the DN211. See "4 .5 The
Semaphore Area" for details of individual areas and registers in the semaphore area.
(1) How to Use the Semaphore Area
Figure 5.3 illustrates the usage of the areas and registers in the semaphore area.
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 read the acknowledgement flag register to check it is "0."
If a value other than "0" is found, write "0" in the 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 wait until "1" is set to
the register.
f) Use a READ instruction to read the response data of the DN211 from the acknowledgement
area when "1" is found in the acknowledgement flag register (top address: 02D0H).
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
Reading the
request area
DN211
internal processing
Responded
Writing in the
acknowledgment area
Figure 5.3 How to Use the Semaphore Area on Requests
(2) 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/acknowledge-
ment flag register. Otherwise, response data could be destroyed.
c) When using a WRITE instruction to write 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.