13 CONTENTS AND REGISTRATION OF USER FRAMES FOR DATA COMMUNICATION
13.3 Considerations for Registering, Reading, and Deleting User Frames
263
13
Considerations for using user frames
■Transmitting/receiving data using user frames
It is necessary to set the user frame number to be used to the buffer memory prior to data transmission/reception (receive
user frames must be set at the startup of C24).
■Data communication procedure when the number for a receive user frame is set from the CPU
module
The procedure to set a receive user frame number form the CPU module and receive data is shown below.
Receive user frame data by performing the following operations sequentially.
• Restart the CPU module when a user frame to be used for data reception was registered from the CPU module.
• Set the receive user frame number to the buffer memory at the startup of C24, and write "1" in the 'User frame use enable/
disable designation' (Un\G173/333) on the buffer memory.
• Start data reception once the value in the user frame use enable/disable designation area on the buffer memory changes to
"2".
• Check whether data is received normally from the target device.
■When additional code data is received during data reception using the nonprocedural
protocol
C24 does not assume that 1-byte data immediately after it is data for the following controls.
• Data received as the start frame, final frame for user frame (Page 250 User Frame Types and Contents During
Communication, Page 259 Transmission/Reception Processing Using User Frame Registration Data)
• Receive end code data
Therefore, do not set a user frame containing data receive additional code data as a user frame for data reception using the
nonprocedural protocol.
■Arbitrary data portion in a message received from a target device
The arbitrary data portion of a message received from a target device cannot include data with the same arrangement (same
code) as the final frame.
■Data bit length of transmission specification
In the following cases, set the data bit length of the transmission specification to 8 bits.
(Set this in "Transmission Setting" of the parameter with Engineering tool for the C24 side.)
• When transmitting and receiving the sum check code of the variable data as binary data (registered code: FFH+EEH,
FFH+F0H, FFH+F4H, FFH+F6H)
• When transmitting and receiving a user frame containing data codes 80H to FFH
User frame
(First frame)
User frame
(Last frame)
Arbitrary data
To Next Page
Loading...
