Set up · tab 4
Sending rules
Optional. With no rules, every linked tag is sent each minute. Rules let the plant decide what may leave its network, and when.
Who decides
The rules live on the plant PC and only its administrators can change them. Nexa receives a read-only copy with each heartbeat and cannot change them. A saved rule applies within seconds, with no restart.
Minutes a rule holds back are reported to Nexa as stretches “not sent by rule”, so the machine’s history shows why there is no data rather than an unexplained gap.
For the whole gateway
| Option | Effect |
|---|---|
| Send live values | Off: nothing goes to the machines’ Live tab in Nexa. The minute data is still sent. |
| Upload only between | Data waits on the PC outside this window (HH:MM–HH:MM, the PC’s time), then goes in one go. |
| Bandwidth cap (KB/s) | The most the gateway may send per second. |
| Send only the tags allowed below | An allow-list. A tag linked in Nexa is read and sent only if it is allowed here, whatever Nexa calls it. |
For each tag
The table lists every linked tag with its machine and server. Select rows, then:
- Allow or Hold back, for the allow-list.
- Edit selected… to set the options below for all the selected tags at once.
Click Save rules when done; the button shows Save rules * while there are unsaved changes.
| Column | Effect |
|---|---|
| Every (s) | How often the tag is sampled. Samples that arrive sooner are dropped. |
| Deadband | Changes smaller than this are ignored. |
| On change only | A minute in which the value did not change is not sent. |
| While running | A minute is sent only if the machine’s running tag was on during it. |
| Around a condition | Sent only around moments that matter. See below. |
Around a condition
For tags that are only interesting when something happens. In Edit selected…, tick Only around a condition and pick another tag of the same machine and what it does: goes above or goes below a value, comes on, or changes.
The tag is then sent from N minutes before (up to 60) to M minutes after (up to 240) each minute in which the condition was met. The minutes before wait on the PC in case they are needed.
What is never thinned
So that production counts and faults stay exact whatever the rules:
- Counters and fault tags ignore On change only and the Deadband.
- Fault tags also ignore Every (s).
Next: start the service.