YASKAWA OYMC V1000, Programming Manual

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YASKAWA ELECTRIC SIEP C710606 10A YASKAWA AC Drive - V1000 PRELIM. Programming Manual 267
2.6 Communications Timing
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2.6 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.
◆
For Command Messages from Master to Drive
In order to prevent overrun and data loss, the master must wait between receiving a response
and sending the same type of command as before to the same slave drive. The minimum wait
time depends on the command as shown in the table below.
Table 2.2 Minimum Wait Time for Sending Messages
Figure 2.5
Figure 2.5 Minimum Wait Time for Sending Messages
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 of time, the master
should try resending the message.
Command Type
<1> If the drive receives command type 1 data, it will perform the command and then respond. However, if it
receives a command type 2 or 3, then either a communication error will result or the command will be
ignored.
Example Minimum Wait Time
1
• Control command (Run, Stop)
• Set inputs/outputs
• Read monitors and parameter values
5 ms
2 • Write parameters 50 ms
<1>
3 • Save changes using an Enter command 3 to 5 s
<1>
Time
Command message Response message Command message
PLC
ψ
Drive PLC
ψ
Drive Drive
ψ
PLC
24 bit length
Master Send
Wait Time