User`s manual

257
CHAPTER 11 DATA COMMUNICATIONS USING USER FRAMES
11
11.2 Data Reception
(c) Reception of combination (1-C)
• In this method, start of data transmission from the external device to the programmable controller CPU side
is notified by the first frame, after which arbitrary data of a fixed length is repeatedly transmitted from the
external device.
• Any reception data prior to the first frame will be ignored. After the first frame is received, all later reception
data is treated as arbitrary data.
• The Q series C24 will begin reception processing when data of the same arrangement as the first frame is
received. A read request will be repeatedly performed to the programmable controller CPU when arbitrary
data equaling the received data count initially set in the Q series C24 is received.
• The received data count initially set in the Q series C24 should be a data count for arbitrary data (fixed
length) transmitted from the external device.
• Reception processing via the receive complete code initially set in the Q series C24 will not be performed.
The reception data for the receive complete code will be treated as arbitrary data.
(2) Reception with the first frame (combination 1-D, 1-E) (reception using Format-
1)
• In this method, arbitrary data of exclusive format-1 received data count initially set in the Q series C24 is
transmitted from the external device together with the first frame.
The data length for the arbitrary data in the reception message that can be handled by the programmable
controller CPU side
*1
can be specified for each data reception frame combination (up to four combinations).
• Any reception data prior to the first frame will be ignored.
• The Q series C24 will begin reception processing when data of the same arrangement as the first frame is
received. When arbitrary data equaling the exclusive format-1 received data count is received, the arbitrary
data is stored in the reception area of the buffer memory and a read request is performed to the
programmable controller CPU.
• Exclusive format-1 received data count initially set in the Q series C24 should be a data count for arbitrary
data to be received. The received data count initially set in the Q series C24 is not used.
• Reception processing via the receive complete code initially set in the Q series C24 will not be performed.
The reception data for the receive complete code will be treated as arbitrary data.
By specifying a user frame, in which only ACK (06H) is registered, as the first frame and also exclusive
format-1 received data count for arbitrary data as 0 bytes, a read request will be performed to the
programmable controller CPU upon the reception of a 1-byte ACK.
First frame
Arbitrary data
Equaling the received
data count
Stored in the
reception area
Equaling the received
data count
Stored in the
reception area
Reception
data
Ignored
: Reception start timing
: Receive complete timing (read timing)