E6581315
5
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
(
,
).
“Parameter Name
and
, Communication Number. 0807 and 0829”
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.
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 19,200/38,400 bps) after receipt of a
frame, the entire frame is assumed to have reached and information in it is analyzed. For this rea-
son, an interval corresponding to at least 3.5 bytes of data must be placed between frames.
When sending a significant data set using two or more frames, an interval corresponding to at least
1.5 bytes of data must be placed between frames. If an interval corresponding to 1.5 bytes or more
is not placed, the contents of a frame are analyzed separately from those of the other frames, and
therefore communication are not carried out normally.
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 computer
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.
Frame A
Frame B
[Correct]
1.5 bytes or more
Frame A (1/2)
[
Wrong
]
If divided into two smaller frames, frame A cannot be received as a
single frame.
Frame A (2/2)
3.5 bytes or more
Frame B
Note: Correct if the interval corresponds
to less than 1.5 bytes of data.
Note: An inverter cannot receive frame
B before it finishes analyzing the
contents of frame A.
