Mitsubishi Electric MELSEC iQ-R Series User Manual page 47

• A data of which number of digits exceeds the upper limit is received
When "Number of Send Digits of Data" is "Variable Number of Digits", an abnormal digit number error (7D19H) may occur if
the number of digits of received data exceeds the upper limit shown below.
Conversion unit
Word
Double word
• A data whose decimal point position is greater than the number of digits is specified
When "Number of Decimals" is 'Variable Point' in a send packet, a decimal point place specification error (7D21H) may
occur if the decimal point position is greater than the number of digits.
• A data whose number of digits is '0' is received
When "Number of Send Digits of Data" is "Variable Number of Digits", an abnormal digit number error (7D19H) may occur if
the number of digits of received data is '0'.
• A data whose number of digits are fewer than the digits specified in "Number of Send Digits of Data" are received
An insufficient digit number error (7D18H) may occur if data whose number of digits are fewer than the digits specified in
"Number of Send Digits of Data" are received.
Example) When "Number of Send Digits of Data" is set to 4 digits
Conversion variable
Receive data "1" "2"
• A data whose number exceeds "Maximum number of data" is received
When receiving data of which the number exceeds the "Maximum number of data", C24 stores data as many as the
maximum number of data and omits the rest. (A protocol completes successfully.)
• A data that cannot be distinguished between Terminator or a Static data
In received packet data from target devices, C24 needs to be able to discriminate data corresponding to a Conversion
variable from those of a Terminator or a Static data following a Conversion variable.
The reception processing may not be performed normally if they cannot be distinguished.
Example) When the value of Terminator or a Static data following the Conversion variable is used as a Conversion variable,
C24 recognized it as a fixed data following the Conversion variable, verify, and perform reception processing.
Conversion content
ASCII DecimalHEX
ASCII HexadecimalHEX
ASCII DecimalHEX
ASCII HexadecimalHEX
Terminator
"3" ETX
An error occurs when 'Conversion
Variable' of the received data ends up
with three digits while the setting of
"Number of Digits of Data" is four
digits.
Upper limit of number data to be received
5 digits
4 digits
10 digits
8 digits
2 DATA COMMUNICATION USING PREDEFINED PROTOCOL
2
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2.3 Packet