Contents
Cirrus Link Resources
Cirrus Link Website
Contact Us (Sales/Support)
Forum
Cirrus Link Modules Docs for Ignition 7.9.x
Inductive Resources
Ignition User Manual
Knowledge Base Articles
Inductive University
Forum
Creating alarms on MQTT tags is a simple process and is no different than creating alarms on any other Ignition tag (as documented here). However, there are some best practices that one should follow depending on the location of these MQTT tags and application specific use cases.
As stated previously, configuring alarms on MQTT Tags is no different than creating alarms on any other Ignition tag. However, when creating alarms on MQTT Engine tags, one must consider the following:
The following two sections will provide details around the considerations above.
Deleting an MQTT Engine tag will result in a loss of alarm configuration. Deleting MQTT Engine tags can be required in certain cases. One example is if UDTs are being propagated from the Edge and the UDT definition on the Edge has been updated. This requires one to delete all instances of the UDT under MQTT Engine and delete the corresponding UDT definition so that it can be recreated/updated at MQTT Engine for the Edge side changes to take affect. There are two options for persisting alarm configuration in this case and they are as follows:
Depending on one's project requirements, triggering alarms on historical data from the Edge Gateway may be necessary. In this case, MQTT Engine and MQTT Transmission module configuration must enable direct writes of historical metrics to MQTT Engine Tags and MQTT Transmission must flush history in-order. See this documentation for more details on these configuration requirements.
Creating alarms on Ignition tags being consumed by MQTT Transmission on the Edge Gateway requires no special configuration; simply create the alarm on the desired tag as documented here.
A common scenario beyond simply creating the alarm is propagating the alarm to the Central Gateway so it can be managed on the Edge, but present at both the Edge and Central Gateway. In Ignition 8, Cirrus Link MQTT modules used to allow for alarm configuration to be propagated from the Edge side tag to the MQTT Engine tag using the "Filtered Properties" feature. This is no longer possible as of MQTT modules version 4.0.6 due to potential timing issues around alarm evaluation at the Central Gateway that could result in incorrect evaluation. The recommended best practice for alarm propagation from the Edge to the Central Gateway is to use the Ignition Gateway Network to propagate alarms between gateways.