Communication Processing By The Inverter; Timeout Processing; Start Code Not Detected; Binary-Format Message - Sanken SVCO6 Instruction Manual

⑯

Communication processing by the inverter

●
If an error is detected in a message from the computer, the inverter executes the following processing:
1) ASCII-format message
①
Parity error, SUM error, or undefined command code
The inverter returns an error message with the command code ―?‖ and a one-byte communication error
code for DT.
Example) When inverter number is ―1‖
* 0 1
②
DT data too long or short, or data cannot be interpreted
The same error processing as ① is executed if a message in data defined by a code is too long or short,
or the received message data cannot be interpreted.
③

Timeout processing

The receive status is terminated forcibly if the entire message cannot be received within 150ms after
receiving start code. The inverter returns communication error code ―d‖.
④

Start code not detected

If data is being received without a correct start code, the above error is reported after a correct start code
is detected.
⑤
List of communication error codes
―s‖: Checksum error
―u‖: Command code not defined
―d‖: Abnormality of data length and format
⑥
Other errors
The timeout processing applies to other errors related to message reception from a computer. The
computer returns no response.
2)

BINARY-format message

When an error is detected in a received message, the inverter returns an error message to the computer
with OP set to ―?‖ and ST set to 1 (BINARY).
①
Abnormality detection item
Parity error, SUM error, undefined command code, or message data too short (receive timeout)
Example) BINARY format
@ IN
⑰
Message transmission and reception between inverter and computer
1） Basics
①
The serial communication protocol is based on a procedure for an inverter to respond to a computer
command. Whenever a command is received from a computer, the inverter returns a response. If the
computer sends more commands to the inverter without waiting for a response from the inverter, the
inverter may not work normally.
②
Due to an inverter or communication line fault, however, the computer may not be able to receive a
response from the inverter. To prevent the response wait status from locking the communication
sequence, the computer should use a receiver timeout of two seconds or longer.
③
The following commands are exceptions:
1) Command Z: The command to automatically notify the computer of an alarm, the transmission of
this command is not influenced by computer command.
? DT SUM EM
? ST SUM
- 277 -
7-4 Serial Communication Function