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4-11
Chapter 4. CPL Communication
2. Error response
If there is an error in the instruction message so that data cannot be read out
normally, an error response is returned.
The figure below shows an example of an error response. ("**" stands for the error
code.)
Termination code (** = an error code)
02H 30H 31H 30H 30H 58H *H *H 03H ??H ??H 0DH 0AH
STX 0 1 0 0 X * * ETX ? ? CR LF
Data link layer Application layer Data link layer
Handling Precautions
•
The data address, read count, value to write, and data to read must conform to
the following rules.
•
A decimal value with four or fewer digits must be converted to a four-digit
hexadecimal value.

Ex.: Decimal value “0” is converted to “0000” (30H, 30H, 30H, 30H).

Ex.: Decimal value “123” is converted to “007B” (30H, 30H, 37H, 42H).
•
A negative value is converted to the 2's complement of a four-digit
hexadecimal value.

Ex.: Decimal value “−123” is converted to "FF85" (46H, 46H, 38H, 35H).
(The value is not preceded by a minus sign).