None Handshake - Mitsubishi Electric MELSEC iQ-R Series User Manual

None handshake

This section shows the operation flow to send messages without using handshakes.
SECS/GEM communication software that receives a message from the host turns the trigger relay for reception notification
ON and then OFF.
Similarly, the transmission request relay turned ON by the Programmable Controller CPU should be turned OFF by the
Programmable Controller CPU itself.
The following section is an example of when receiving a message from the host.
Programmable
controller CPU
(4)
(5)
(6)
(7)
The transmission request
relay is turned on.
It is turned off after a
predetermined hold time.
(1) A message is received from the host.
(2) The SECS/GEM communication software stores the received data in the shared memory/device.
(3) SECS/GEM communication software turns the receive notification trigger relay ON (OFF→ON control) to inform the Programmable Controller CPU of the
reception.
This receipt notification trigger relay will remain ON for a predetermined time and then be turned OFF by SECS/GEM communication software itself.
(4) The Programmable Controller CPU detects the receive notification trigger on state.
(5) After the programmable controller CPU acquires the received data in the shared memory/device, the received data is processed by a program of the
programmable controller CPU.
(6) The programmable controller CPU configures the sending data to the shared memory/device.
(7) The Programmable Controller CPU turns the transmission request trigger relay ON (OFF→ON control).
Note that this sending request trigger relay is switched OFF by the programmable controller CPU after a prescribed hold time.
(8) The SECS/GEM communication software detects the sending request trigger.
(9) The SECS/GEM communication software acquires the data of the item section of the sending transaction from the shared memory/device of the
programmable controller CPU.
(10) After editing the data into a SECS- transaction message, SECS/GEM communication software transmits the message to the host.
The procedure when data is sent from the programmable controller CPU is the same as above.
SECS/GEM communication
software
Shared memory/
Device
(2)
(3)
The receive notification
relay is turned on.
It is turned off after a
predetermined keep time.
(8)
(9)
Host
(1)
(10)
7 BASIC FUNCTIONS
7.3 Programmable Controller CPU Link Function
7
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