Mitsubishi MELSEC L Series User Manual page 223

(2) Precautions when using user frames
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9 CONTENTS AND REGISTRATION OF THE USER FRAMES FOR DATA COMMUNICATION
(a) To send/receive data using the user frames, it is necessary to set the user
frame number to be used in the buffer memory prior to data
transmission/reception (receive user frames must be set at the startup of the
Q series C24).
The user frame number to be used can be set from the programmable
controller CPU. However, please try to register frames using the utility
package (GX Configurator-SC) of the Q series C24.
(b) Set the receive user frame number by the programmable controller CPU to
show the procedure to receive data.
Receive user frame data by performing the following operations sequentially.
(chapter 11 explains steps 2) and 3).)
1) If an user frame used in data reception was registered from
programmable controller CPU, restart programmable controller CPU.
2) When starting the Q series C24, set the receive user frame No. to the
buffer memory and write [1] to buffer memory user frame use
enable/disable designation area (addresses: AD
3) After the value of the buffer memory user frame use enable/disable
designation area changes to [2], start receiving data.
4) Check if the data from the external device was received normally.
(c) If the Q series C24 receives additional code data while receiving data with
the non procedure protocol, it does not assume that the last byte of data is
the following control data.
• Data received as user frame first frame, last frame (See Sections 9.1 and
9.2.)
• Receive complete code data
Therefore, do not set a user frame containing data receive additional code
data as a non procedure protocol receive user frame.
(d) The arbitrary data area of a message received from an external device
cannot include data with the same contents (same code) as the last frame.
(Example)
User frame
(first frame)
(e) In the following cases, set the data bit length of the transmission
specification to 8 bits.
(It is set in the "transmission setting" of switch setting by GX Developer on
the Q series C24 side.)
1) When transmitting and receiving the sum check code of the variable data
as binary data
(Write code: FF
2) When transmitting and receiving a user frame containing data codes 80
to FF
H
Arbitrary
dat area
, EE /FF , F0 /FF , F4
H H H H H
/14D ).
H H
User frame
(last frame)
/FF , F6 )
H H H
H
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