User Manual of A90 Series Inverter
295
t0
Frame 1 Frame 2 Frame 3
At least 3.5
characters
At least 3.5
characters
3.5 characters
4.5 characters
< 1.5 characters
> 1.5 characters
Exceptional
frame
Normal
Fig. 0-3 Schematic Diagram of Normal and Exceptional Data Frames
12.4.2 Data frame processing
Upon receiving a frame data, the system will first perform preprocessing to determine
whether it is a legal frame sent to this machine and check whether the data is correct,
followed by final processing. If the received frame is not legal, the data will not be sent
back. If the received frame is legal but incorrect, the corresponding exceptional message
frame will be sent back.
Legal frame: Meet the address (local or broadcast) and length (not less than 3)
requirements.
Correct frame: It is a legal frame with a correct memory address. The memory content
is within the defined range and can be processed at present.
12.4.3 Response delay
The response delay (depending on the function code F10.04) is defined as the time
interval from the reception of valid data frame
[7]
(data in the RS-485 network, different
from the command sent by the keyboard) to data parsing and return. Since the starting and
ending characters are defined in the standard protocol, it is impossible to avoid response
delay, at least “3.5-character time interval + 1 ms (chip stabilization time of 485 protocol,
t
wait2
)”. The specific minimum time interval is related to the baud rate. If the baud rate is
9600bps, the minimum response delay is 5ms (3.5×10/9600+1=4.64≈5).
If the communication data involves EEPROM operation, the time interval will
be longer.
[7]: Valid data frame: Sent by the external master station (not keyboard) to this
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