
78
Details of the Data Exchange Methods
Section 6-3
6-3-2
Data Exchange Method No. 2
The ASCII Unit independently reads/writes the CPU Unit memory during the I/
O refresh period.
PC READ@
The ASCII Unit reads the CPU Unit memory as specified in the PC READ@
command.
1,2,3...
1.
PC READ@ command executed.
2.
The ASCII Unit reads data during the I/O refresh period (the ASCII Busy
Flag goes ON).
3.
When the PC READ@ command data transfer is completed, the ASCII
Busy Flag goes OFF.
The following example is for a C200HX/HG/HE PC.
PC WRITE@
The ASCII Unit writes to the CPU Unit’s internal I/O memory, as specified in
the PC WRITE@ command.
1,2,3...
1.
PC WRITE@ command executed.
2.
The ASCII Unit writes data during the I/O refresh period (the ASCII Busy
Flag goes ON).
3.
When the PC WRITE@ command data transfer is completed, the ASCII
Busy Flag goes OFF.
CPU Unit
ASCII Unit
2. Via PC READ command
255 words max.
ASCII Unit on standby
until here.
None
20 words max. per cycle (except as shown below)
127 words max. per cycle (C200HX/HG/HE or CS1-series PC and when
number of transfer words per cycle is 127
words in DM m + 4 in the Setup Area)
1.
At I/O refresh
DM 0300
0301
0302
PC READ "@D, 300, 3, S3H4"; B (1)
B (1)
B (2)
B (3)
Содержание C200H-ASC11
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