Monitored Values

 

This section covers Digital Values to Monitor, Integer Values to Monitor and Float Values to Monitor. Each set of settings allows you to choose up to 32 values of the designated type (digital, 16 bit signed integer or single precision floating point) to monitor.

 

Each monitored value can be named independently via the group instance name setting. Slashes ('/') can be entered as a part of the name, which is useful since the MQTT protocol treats slashes as group delimiters. This allows values of different types to be logically grouped together.

 

Each monitored value can be independently configured for alarming or for publishing on change. For all values, choose a Modbus register to monitor. Floating point values will need two registers.

 

Next, for digital values, select the Enable Monitoring option, select the Publish on Alarm option, and then the alarm state. For integer or digital values, choose the Enable Monitoring option, select the Publish on Alarm option, and enter High Level and Low Level alarm limits. To disable a specific alarm type *high or low) on a point, set the limit to the maximum or minimum value, or to a very large or very small value.

 

When the value in the register exceeds the limit, the value will be published. When the value returns to normal, the value will be published again. See the Operational Details section for what the published data looks like.

 

Use the Publish On Change settings to publish a value when it changes. For digital values, then value will be published whenever it changes. For integer and float values, you can specify a deadband either as a percent of the value or as a fixed value. When the value changes by more than the deadband, it will be published. Select the Publish On Change setting to enable publishing when the value changes.

 

Note that when the deadband is specified as a percentage of the value that the actual deadband range is always changing. For example, if the last published value is 1000, and the deadband is 10%, the value will be published when it is less than 900 or greater than 1100. However, if the last published value was 10000, the value would be published when it's less than 9000 or greater than 11000. The deadband went from +/-100 to +/-1000;

 

Each monitored value has an Enable Subscribe option. This option has no effect unless the Publish Format in the MQTT Server Settings group is Sparkplug B, and the Enable Subscribe option in the MQTT Server Settings group is enabled.

 

If these preconditions are met, the Enable Subscribe option on each monitored value allows the value of the underlying Modbus Register to be updated via MQTT. When this option is not selected, changes are not possible.

 

Updates to the value will be rejected unless the Enable Monitoring and Publish on Change options are also enabled. In other words, Enable Subscribe, Enable Monitoring and Publish on Change must all be selected before the value can be updated via MQTT. The global Enable Subscribe setting must also be selected, and the Publish Format must be Sparkplug B.

 

When the value is updated via MQTT, it is also immediately published via MQTT. This forms a feedback loop that verifies that the value was written correctly. Depending on communications speed, this process can take a few seconds.

 

Units

Integer and Float values allow you to specify Units. This value is only used when the Publish Format is Sparkplug B. When the Publish Units option is selected in the MQTT Server Settings group, the string value in Units is pushed the EngUnit tag in the host.

 

Any value can be added to a reporting group. Note that alarming or publishing on change does not need to be enabled on a value for it to be included in a periodic report.