C.6 Communications Timing
C.6 Communications Timing
To prevent overrun in the slave drive, the master should wait a certain time between sending messages to the same drive.
In the same way, the slave drive must wait before sending response messages to prevent an overrun in the master. This
section explains the message timing.
♦ Command Messages from Master to Drive
The master must wait for a specified time between receiving a response and re-sending the same type of command to the
same slave drive to prevent overrun and data loss. The minimum wait time depends on the command as shown in the
table below.
Table C.2 Minimum W ait Time fo r Sending Messages
Command Type
Example
Minimum Wait Time
• Control command (Run, Stop)
• Set inputs/outputs
• Read monitors and parameter values
5 ms
2
• Write parameters
H5-11 = 0: 50 ms
H5-11 = 1: 200ms
<1>
3
• Save changes using an Enter command
200 ms to 2 s, depending on the number of
parameters that were changed <1>
<1> I f the drive receives comm and type 1 data during the minim um w ait tim e, it will perform the comm and and then respond. However, i f it
receives a comm and type 2 or 3 during that time, either a com m unication error will result or the comm and will be ignored.
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C o m m a n d m e s s a g e
R e s p o n s e m e s s a g e
C o m m a n d m e s s a g e
T im e
2 4 b it le n g th
J t_
M a s te r S e n d
W a it T im e
F ig u r e C .6 M in im u m W a it T im e f o r S e n d in g M e s s a g e s
A timer should be set in the master to check how long it takes for the slave drive(s) to respond to the master. If no
response is received within a certain amount o f time, the master should try resending the message.
♦ Response Messages from Drive to Master
If the drive receives a command from the master, it will process the data received and wait for the time set in H5-06 until
it responds. Increase H5-06 if the drive response causes overrun in the master.
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C o m m a n d m e s s a g e
R e s p o n s e m e s s a g e
C o m m a n d m e s s a g e
T im e
2 4 b it le n g th
s e ttin g
F ig u r e C .7 M in im u m R e s p o n s e W a it T im e
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YASKAWA ELECTRIC SIEP C710616 33D YASKAWA AC Drive L1000A Technical Manual