Omron C200H-ASC11, Manual, Page: 85 / 301

76
Details of the Data Exchange Methods
Section 6-3
PC READ When the ASCII Unit receives an ON Write Bit from the CPU Unit, it reads the
memory words specified in the allocated IR/CIO words, and stores the con-
tents in the specified variable.
1,2,3... 1. Request using the PC READ command.
2. Write Bit turned ON using the OUT instruction in the ladder diagram.
3. During the I/O refresh period, the Write Bit (IR/CIO n bit 01) from the CPU
Unit to the ASCII Unit turns ON.
4. At the next I/O refresh period, the ASCII Unit reads data and the ASCII
Busy Flag is turned ON by the system.
5. When the ASCII Busy Flag changes to ON, the Write Bit is turned OFF in
the ladder diagram.
6. Once the PC READ command’s data transfer has been completed, the
ASCII Busy Flag is turned OFF by the system.
The following example is for a C200HX/HG/HE PC.
CPU Unit
#
❍❍❍❍
#
❍❍❍❍
ASCII Busy
Flag
n + 3: IR 103
n + 4: IR 104
IR n bit 01 (Unit
No. 0: IR 10001)
3. Write Bit (trigger)
at I/O refresh
Transfer Data Area (e.g., DM)
No. of Transfer Words (e.g., 3)
3. Allocated I/O
(at I/O refresh)
First word of the read I/O
memory at PC READ (e.g., 100)
ASCII Unit
1.
4. Via PC READ command
3 words
255 words max. per
command
At next I/O refresh
ASCII Unit on standby up
until here.
20 words max. per cycle (except as shown below)
127 words max. per cycle (C200HX/HG/HE or CS1-series PC and
number of transfer bytes per cycle is 127 words
at DM m + 4 in the Setup Area)
2.
IR n+5
bit 00