User`s manual

309
CHAPTER 12 TRANSPARENT CODES AND ADDITIONAL CODES
12
12.5 Handling Transparent Codes and Additional Codes During Bidirectional Protocol Data
Communication
12.5 Handling Transparent Codes and Additional Codes
During Bidirectional Protocol Data Communication
The following explains the handling of transparent codes and additional codes during data communication using the
bidirectional protocol.
(1) The additional code designation data will be added to or deleted from the data
that is sent or received.
(2) Communication data for which transmission/reception processing of
transparent codes and additional codes is performed includes the message
data length, data section and error code.
Such processing is not performed for the head code (ENQ, ACK, NAK) and sum check code of a message.
The Q series C24 performs the following processing during data transmission/reception.
(a) When an additional code set for reception is detected during data reception, the
additional code data is removed and the immediately succeeding one-byte data is
processed for reception as part of the receive data.
When transparent code/additional code data set for transmission is detected during transmission of a message
in response to data reception, the additional code designation data is added immediately before, and is then
transmitted.
(b) When transparent code/additional code data set for transmission is detected during
data transmission, the additional code designation data is added immediately
before, and is then transmitted.
When an additional code set for reception is detected while a message is being received in response to data
transmission, the additional code data is removed and the immediately succeeding one-byte data is processed
for reception as part of the receive data.
*
*
*
HLHL
E
N
Q
A
C
K
N
A
K
External device side
Data section
(Designated
transmission data)
Data
length
Sum
check
code
(When
normal)
Error
code
Transmission sequence
Applicable data range
(When
abnormal)
Programmable
controller CPU
side
LH