Communication Protocol; About The Handling Of Received Frames - Toshiba Tosvert VF-S15 Series Instruction Manual

3. Communication protocol

VF-S15 supports the Toshiba inverter protocol and a 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, the data
flames are not only data from the computer to an inverter but also the response from an inverter to
the computer. Therefore, an interval corresponding to at least 3.5 bytes should be placed between
the time when the 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 immedi-
ately 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
fram e when the interval corresponds to less than 1.5 bytes of data.
Phone: 800.894.0412 - Fax: 888.723.4773 - Web: www.clrwtr.com - Email: info@clrwtr.com
Data Range: 0, 1 (Initial value: 0)
0: Toshiba inverter protocol (Includes inter-drive communication)
1: Modbus RTU protocol
* A parameter change is reflected when the inverter is reset, such as in power off.
Frame A
Fram e A (1/2)
3.5 bytes or more
Frame B
Note: An inverter cannot receive frame
3.5 bytes or more
B before it finishes analyzing the
contents of frame A.
Frame A (2/2)
5
E6581913
Frame B