Azbil C1M - Description of Commands; Application Layer; Continuous Data Read Command (RS Command)

7-7
Chapter 7. CPL Communication Function
7 - 3 Description of Commands

Continuous data read command (RS command)
This command reads data from consecutive addresses in one message.
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Instruction message
This is a command—in one message—to read data from consecutive word
addresses starting from the specified address. The figure below shows the structure
of the application layer of a “read” instruction message.
R S , 9 1 0 1 W , 1
(1) (2) (3) (2) (4)
Application layer
(1) Continuous data read command
(2) Data delimiter
(3) Starting word address
(4) Read data count
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Response message
If an instruction message is received successfully, a response message appropriate
for the command is returned.
The figure below shows the structure of the application layer of a response message
for a read command.
• Normal termination (reading of single data record)
0 0 ,
(1) (2) (3)
• Normal termination (reading of multiple data records)
0 0 , , ,
(1) (2) (3) (2) (4) (2) (5)
• Abnormal termination
X X
A termination code indicating an error is entered in place of XX.
7 - 6 List of Termination Codes (p.7-15) (for details about termination
codes)
(1)
(1) Termination code
(2) Data delimiter
(3) Read data 1
(4) Read data 2 to (n−1)
(5) Read data n
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Maximum read data count per message
64 words