Handshake (For Each Message) - Mitsubishi Electric MELSEC iQ-R Series User Manual

Handshake (for each message)

This section shows the operation flow to link trigger relays by handshakes for each message.
The following section is an example of when receiving a message from the host.
Programmable
controller CPU
(4)
(5)
The receive
notification relay is
turned off
(6)
(7)
The transmission
request relay is turned
(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.
(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, it turns the reception notification trigger relay OFF, and then
performs response confirmation. (ON to OFF control)
The reception 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).
(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.
(11) The sending request trigger relay is switched OFF. (ON to OFF control)
The procedure when data is sent from the programmable controller CPU is the same as above.
The programmable controller CPU stores the sending data in the shared memory/device, and then turns the sending request
trigger relay ON.
During return receipt, the SECS/GEM communication software stores the received data in the shared memory/device, and
then switches the reception notification trigger relay ON.
After this, the programmable controller CPU acquires the data.
7 BASIC FUNCTIONS
54
7.3 Programmable Controller CPU Link Function
Shared memory/
Device
The receive
notification relay is
turned on.
on
The transmission
request relay is turned
SECS/GEM communication
software
(2)
(3)
(8)
(9)
(11)
off
Host
(1)
(10)