6 F 3 B 0 3 6 4
66
(7) The usage of Output/Input Data Semaphore (for synchronous transmission mode
alone)
Figure 4.4 indicates the relation between output data semaphore (polling / bit strobe) and input data
semaphore. Oblique lines parts indicate each of the semaphore values is set to the "1".
processing
processing
processing
T2/T2E/
T2N
output
comple-
tion "0"
completion
"0"
completion
output
instruction "1"
DN211
Intput data
Output data
Writes in output
Reads from
Writes in output
Figure 4.4 Use of Semaphores in Synchronous Mode
(8) Cautions in Using the Input/Output Data Area
• The input data semaphore register is used both for the polling mode and the bit strobe
mode. Therefore, when some slave devices use the polling mode while other slave
devices use the bit strobe mode, set data input/output processing in the alternative
way like :
polling mode processing completion
→
bit strobe mode processing completion
→
polling mode processing completion
→
bit strobe mode
→ …
• Don't allow the WRITE instruction to execute in the input data area/input data
semaphore register. Otherwise, input data could be destroyed.
• When you write data in the polling output data area/bit strobe output data area with the
WRITE instruction, be careful of the top address of the area and the data size to be
written. Otherwise, data could destroy those in another area, causing the DN211
and/or slave devices to get malfunctioned.
