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VFD68 Variable Frequency Drives
93
Message Format
Query
The master sends a message to the slave (VFD) at the specified address.
Normal Response
After receiving the query from the master, the slave executes the requested function and returns the
corresponding normal response to the master.
Error Response
If an invalid function code, address, or data is received, the slave returns it to the master. When a response
description is returned, the error code indicating that the request from the master cannot be executed is added.
No response is returned for the hardware-detected error, frame error, and CRC check error.
Broadcast
By specifying address 0, the master can send a message to all slaves. All slaves that received the message
from the master execute the requested function. In this communication, the slaves do not return a response to
the master.
Note:
The VFD performs the function independently of the VFD station number setting (P.117) during
broadcast communication.
Table 88: Data Check Time
Item
Check Time
Various Monitors, Operation Command, Frequency Setting (RAM)
< 20 ms
Parameter Read and Write, Frequency Setting (EEPROM)
< 50 ms
Parameter Clear or All Clear
< 5 s
Reset Command
No answer
Broadcast Communication
Master
(programmable controller)
Slave
(VFD)
Query Message
No Response
Query Communication
Master
(programmable controller)
Slave
(VFD)
Query Message
Response Message
Data Absence Time
(3.5 bytes or more)
VFD Response Time
(Data Check Time)
Figure 56: Message Format