Azbil F4Q, User Manual

Page: 26 / 76

4-10
Chapter 4. CPL Communication
2. Read start data address

Role : This specifies by a four-digit hexadecimal number the first data
address to be read.

Description :
6 - 2 Communication Data Table (p. 6-3)
(for the relationship
between data addresses and read data)
Do not add “W” (57H) to the end of the data address.
3. Number of read data records

Role : This specifies how many consecutive pieces of data to read, starting
from the data address specified with four hexadecimal digits.

Description : Up to 10 data records can be read in one message.
z Response message to the RD command
If the message in the data link layer is correct, a response message appropriate for
the contents of the instruction message is returned.
The data in the application layer is the termination code (two decimal digits) and
the number of pieces of data to read (four hexadecimal digits × number of items),
which is specified by the instruction message. (However, in the case of an error
response, read data is not included.)
As in the case of RS commands, a response message always includes a termination
code.
1. Normal response
Returns the specified number of data records as a four-digit hexadecimal number.
• The range of the data records depends on the individual data read.
• Data is expressed without a decimal point.

Ex.: The decimal number “20.0” is expressed as “00C8.”
• Since the data length is fixed, commas (2CH) are not added to delimit data.
• The figure below shows an example of a normal response. (two pieces of data are
read normally).
Termination code (00 = normal)
1st data record that was read
2nd data record that was read
02H 30H 31H 30H 30H 58H 30H 30H 30H 30H 37H 42H 30H 33H 36H 36H 03H 44H 41H 0DH 0AH
STX 0 1 0 0 X 0 0 0 0 7 B 0 3 6 6 ETX D A CR LF
Data link layer Application layer Data link layer