Rievtech ELC Series - Page 235

EN
Programmable Relay ● User Manual for ELC, EXM and PR Series 235 2020 v6.0 ● © Rievtech Co.,
Ltd. ● www.rievtech.com
Publish with MQTT
Description of Function
After successfully connecting to the MQTT server, activate this function block to publish the message to a topic in the MQTT
server.
Connection
Description
En
You enable/disable the block with the signal at input En (1/0).
Parameter
Retained:
Typically, if a publisher publishes a message to a topic, when no one subscribes to the topic, then
the message will be discarded (not retained) by the MQTT server.
However, the publisher can tell the MQTT server to keep the last message of the topic by setting a
reserved message flag. When a device subscribed to this topic goes online, the MQTT server sends
the retained information to the subscriber.
You can check this option to implement this ‘information retention’ feature. A powered-down device
can receive the last message of its subscribed topic after powering on.
QoS Level:
QoS 0(no answer) or QoS 1(answer). If you wish to receive a response from the MQTT server, select
‘QoS 1’.
Publish interval time:
Publish timer setting. If enabled, the xLogic will publish the message to the MQTT server every x
seconds. If disabled, the message will only be sent once.
Publish topic:
Set when creating a new topic project on the MQTT server.