To prevent overrun of the slave side, the master cannot send a message to the same drive for a selected length of time.
To prevent overrun of the master side, the slave cannot send a response message to the master for a selected length of time.
This section gives information about message timing.
Command Message from Master to Slave
To prevent data loss and overrun, after the master receives a message from the slave, the master cannot send the same type of command message to the same slave for a selected length of time. The minimum wait time is different for each type of message. Refer to Table 1 to find the minimum wait times.
Table 1. Minimum Wait Time to Send a Message
|
Command Type
|
Example
|
Minimum Wait Time
|
|
1
|
|
5 ms 1
|
|
2
|
Writing a parameter
|
50 ms 1
|
|
3
|
Writing of modified data with the Enter command
|
3 to 5 s 1
|
Figure 1. Minimum Wait Time to Send a Message
You must set the timer in the master to measure the length of time for the slave to respond to the master. If you set the timer, but the slave does not send a response message in a specified length of time, the master will send the message again.
Response Message from Slave
The slave receives the command message from the master then processes the data it received. The slave then waits for the time set in H5-06 [Drive Transmit Wait Time] then sends a response message to the master. If overrun occurs on the master, increase the wait time set in H5-06.
Figure 2. Response Wait Time
1
When the drive receives a message in the minimum wait time, it does command type 1 and sends a response message. If the drive receives command type 2 or command type 3 messages in the minimum wait time, it will trigger a communications error or the drive will ignore the command.