E Computer Link/Pc Link Protocol Minimum Transmission Delay Times - Toshiba V Series User Manual

Appendix E Computer Link/PC Link Protocol
Minimum Transmission Delay Times
(1) Minimum delay time for computer link protocol transmission
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The minimum delay time from the point the host computer issues a request to the S
controller to the point a response is received for computer link protocol transmission
is:
(Computer link protocol transmission minimum delay time)
= (Host computer transmission processing time) + ("S controller response time)
The S controller response time depends on the following three instructions:
• Request commands of the computer link
• Instructions included in the user program of the S controller
• S controller main task - scan time
The processing time required for response text creation differs for each request
command as listed in Table E.1. If this processing is not completed in the empty
space within the first scan it will be divided across multiple scans continuing with the
next scan.
Table E-1 Computer Link Response Text Creation Processing Times
Command Type
DR 1 word
Continuous, 32 words
Multiple types, 16 words
DW 1 word
Continuous, 32 words
Multiple types, 16 words
RT
ST
WT
When the S controller receives a computer link protocol transmission request, it
performs computer link response text creation processing. Normally, the response
text creation processing is performed in parallel with user program execution.
However, if the user program includes the following instructions, the execution of
those instructions takes precedence.
Therefore, if the user program includes large numbers of these instructions, the
response text creation processing will be performed in the empty space in each scan
that follows the user program execution time.
[RTC instructions]
Response text creation time (ms)
-
-
-
1.6
2.7
6.2
1.9
6.9
8.1
1.1
0.9
1.7
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