Communication Protocol; About The Handling Of Received Frames - Toshiba TOSVERT VF-nC3 Instruction Manual
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3. Communication protocol
This communication protocol supports the TOSHIBA Inverter Protocol and part of MODBUS-RTU
protocol.
Select the desired protocol from in the following communication protocol selection parameters
(f829).
"Parameter Name f829, Communication Number. 0829"
3.1. About the handling of received frames
To send and receive data frames, a frame synchronization system for locating the start and end
points of each frame is defined with time for which no data is sent (time interval equivalent to the
time required to send 3.5 bytes of data).
If no data is sent for the time required to send 3.5 bytes of data at the current transmission speed
(approx. 4 ms or more at 9,600 bps or approx. 2 ms or more at 19,200 or approx. 1 ms or more at
38400) after receipt of a frame, the entire frame is assumed to have reached and information in it is
analyzed. For this reason, an interval corresponding to at least 3.5 bytes of data must be placed
between frames.
When two or more inverters on the same line are controlled individually one after another, not only
data from the host computer to an inverter but also a response from an inverter to the host com-
puter are transmitted to the other inverters on the line too. Therefore, an interval corresponding to at
least 3.5 bytes should be placed between the time when the host computer receives a response
from an inverter and the time when it sends a frame to the next inverter. Otherwise the return frame
received and the frame that is sent immediately after receipt of the return frame will be recognized
as one frame and communication will not be carried out normally.
[Correct]
[
]
Wrong
If divided into two smaller frames, frame A cannot be received as a single frame when the
interval corresponds to less than 1.5 bytes of data.
Frame A (1/2)
Data Range: 0, 1 (Initial value: 0)
0: TOSHIBA (Includes inter-drive communication)
1: MOUBUS-RTU
* A parameter change is reflected when the inverter is reset, such as in power off.
Frame A
3.5 bytes or more
Frame A (2/2)
3.5 bytes or more
5
Frame B
Note: An inverter cannot receive frame
B before it finishes analyzing the
contents of frame A.
Frame B
E6581657
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