Communications timing, Command messages from master to bypass, Response messages from bypass to master – Yaskawa AC Drive P1000 Bypass Technical Manual User Manual
Page 313: D.6 communications timing
D.6 Communications Timing
To prevent a communications overrun in the slave bypass, the master should wait a certain time between sending messages
to the same bypass. In the same way, the slave bypass must wait before sending response messages to prevent an overrun in
the master. This section explains the message timing.
u
Command Messages from Master to Bypass
The master must wait for a specified time between receiving a response and resending the same type of command to the same
bypass drive to prevent overrun and data loss. The minimum wait time depends on the command as shown in
.
Table D.1 Minimum Wait Time for Sending Messages
Command Type
Example
Minimum Wait Time
1
• Control command (Run, Stop)
• Set inputs/outputs
• Read monitors and parameter values
5 ms
<1>
2
Write parameters
200 ms
<1>
3
Save changes using an Enter command
200 ms to 2 s, depending on the number
of parameters that were changed
<1>
4
Enter with storage to drive EEPROM after initialization
5 s
<1> If the drive receives command type 1 data during the minimum wait time, it will perform the command and then respond. However, if it receives
a command type 2 or 3 during that time, either a communication error will result or the command will be ignored.
Set a timer in the master to check how long it takes for the slave bypass(es) to respond to the master. If no response is received
within a certain amount of time, the master should try resending the message.
u
Response Messages from Bypass to Master
If the bypass receives a command from the master, it will process the data received and wait for the time set in Z3-07 until it
responds. Increase Z3-07 if the bypass response causes overrun in the master.
Time
Command message
Response message
Command message
PLC→Bypass
PLC→Bypass
Bypass→PLC
24-bit length
Z3-07
setting
Figure D.4 Minimum Response Wait Time
D.6 Communications Timing
YASKAWA SIEP YAIP1B 01A YASKAWA AC Drive – P1000 Bypass Technical Manual
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D
MEMOBUS/Modbus Communications