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6. V-Link 3-29
Serial Communications
Sum Check Code (SUM): 2 bytes
Data is added up (SUM), and the lower one byte (8 bits) of the sum is converted into the
2-digit ASCII code (hexadecimal). A sum check code is shown below.
Example: Transmission mode: without CR/LF, with sum check
Command: 20 (data read)
Address: 10 words from $u1000 (03E8H)
When reading, a sum check will be performed as shown below.
Response Code: 2 bytes
[ACK]
This code is received at normal termination.
00H (3030: ASCII)
[NAK]
This code is received at abnormal termination. (ASCII) Refer to the next page for more
information.
NAK: Error Codes
02H: Overrun/Framing error
An overrun or framing error is detected in the received data. Send the command
again.
03H: Parity error
A parity error is detected in the received data. Send the command again.
04H: Sum check error
A sum error occurs with the received data.
06H: Count error
The memory read/write count is “0.”
0FH: ETX error
No ETX code is found.
11H: Character error
A character not used in the received data is found. (other than 0 to F) Check the
character and send the command again.
12H: Command error
An invalid command is given.
13H: Memory setting error
The address or device number is invalid.
STX
V7 Port
number
Command
Read
Words
Memory
Model
Memory
Type
Address System reserved ETX SUM
01H 20H 0AH 00H 00H 03E8H 0 0 0 0 0 0 0 0 0 0H B9H
02H 30H31H 32H30H 30H41H 30H30H 30H30H 30H 33H 45H 38H 30H 30H 30H 30H 30H 30H 30H 30H 30H 30H 03H 42H39H
02H + 30H + 31H + 32H + 30H + 30H + 41H + 30H + 30H + 30H + 30H + 30H + 33H + 45H + 38H
+ 30H + 30H + 30H + 30H + 30H + 30H + 30H + 30H + 30H + 30H + 03H =
4B9H