Mitsubishi Electric MELSEC iQ-R Series User Manual page 245

■Sending SECS messages
When an SECS message is sent from programmable controller CPU to the host, the sent data is stored in the prescribed
register mapped to the corresponding sending message item, and then the sending request trigger relay configured for the
corresponding message is switched ON.
The SECS/GEM communication software detects that the transmission request trigger relay is on, extracts the data of the
corresponding message item from the configured prescribed register, creates an SECS message, and then sends the
message to the host according to the SECS protocol. After sending, the transmission request trigger relay is switched off, and
the Programmable Controller CPU is notified of the completion of sending.
Programmable
Controller CPU
Register
Õ
Ò
Ô
Ó
Sending process
Ø
No. Description
 The sent data is stored in the register specified by the item property definition (Page 68 Item information)

The sending request trigger relay specified by the message property definition is switched ON (Page 65 Message information)

The SECS/GEM communication software detects storage of sent data to the register from the sending request trigger relay of the programmable
controller CPU switching ON

The SECS/GEM communication software reads the sent data from the register of the programmable controller CPU

The SECS/GEM communication software constructs a SECS message based on the imported data, and then sends it to the host
 The sending request trigger relay of the programmable controller CPU switches OFF

Sending completion is reported to the programmable controller CPU by the sending request trigger relay switching OFF
The sending request trigger relay is configured at the "Primary message information" screen or "Secondary message
information" screen. Select the "Transmission Request Trigger" checkbox, and then configure the notification destination.
( Page 65 Message information)
• Configure the transmission request trigger hold time at the message settings screen of the scenario
explorer.
The SECS/GEM communication software confirms that the time trigger relay configured here is ON before it
recognizes that the relay is ON.
• To notify of an error during SECS communication, configure it at the [SECS Error Notification Setting] tab of
the "Option Setting" screen. Select the checkboxes for information to be reported, and then configure the
notification destination. ( Page 99 CA status)
In the case of a sending failure, select the [Sending failure] checkbox, and then configure the relay for
reporting.
SECS/GEM communication
software
Sending process
Ö
×
9 SECS/GEM COMMUNICATION SOFTWARE KNOWLEDGE
Host
Receiving process
9.4 Sending and Receiving Messages
9
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