Yaskawa Z1000U HVAC Matrix Bypass - Manual (Page 441)

F.5 Communications Timing
To prevent a communications 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.
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
slave bypass to prevent overrun and data loss. The minimum wait time depends on the command as shown in Table F.4 .
Table F.4 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
H5-11 = 0: 50 ms
H5-11 = 1: 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 bypass 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.
Command message Response message Command message
Controller →Bypass Controller→Bypass Bypass →Controller
24 bit length
Master Send
Wait Time
Time
Figure F.5 Minimum Wait Time for Sending Messages
Set a timer in the master to check how long it takes for the slave bypass units 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 drive response causes overrun in the master.
Time
Command message Response message Command message
→ → →
24 bit length Z3-07 setting
Controller Bypass Bypass Controller Controller Bypass
Figure F.6 Minimum Response Wait Time
F.5 Communications Timing
YASKAWA SIEP YAIZ1D 01A Z1000U HVAC MATRIX Drive Bypass Technical Manual 441
F
Metasys N2 Network Protocol