Switching relays

A relay board has two outputs, Relay 1 and Relay 2. Each one is a switch that can be wired to something you want to control from a distance: a pump, a heater, a fan, a vent motor.

CropWatch sends the board a command over the same radio network your sensors use, and the board answers with its new state. A relay board listens all the time, so a command usually reaches it and gets an answer within a few seconds. Between commands the board also reports its state on its own schedule.

Open the relay with the Details button on its card, or from the list of sensors at its location. Below the header that every sensor page has, the page holds, from top to bottom:

• Two cards, “Relay 1” and “Relay 2”: each headed “Current state”, with a switch picture, a label such as “🟢 ON” or “🔴 OFF”, and the buttons “Turn On” and “Turn Off”. The switch picture only shows the state; you cannot flip it.
• “Timed pulse control”: a panel that opens when you press it, for switching a relay on for a set number of seconds.
• “Last updated”: the date and time of the board's latest report.
• “Relay History”: every state change and every command in the chosen period.

While the page is open, CropWatch fetches the board's state every 30 seconds, so a change made by a colleague or by an alert rule shows up without reloading.

A card that reads “Unknown”, with “No confirmed relay telemetry yet.” under it, means CropWatch has no report of that relay's state yet. Its buttons still work for anyone allowed to switch, so a command can still be sent.

As soon as the command is sent, the card shows the state you asked for, with an amber “Pending confirmation” label and the line “Command sent. Waiting for the device to confirm.” What happens next depends on the board:

“Not confirmed yet” does not mean the relay failed. Either the command did not arrive, or it worked and only the answer was lost; at this point CropWatch cannot tell which. The card keeps showing the state you asked for, labelled “Not confirmed yet”, with the line “The device hasn't confirmed this yet. It will update automatically when the device next reports.” When the next report arrives, the card shows what the board says, with the green or amber message described above. You can leave the page in the meantime: Relay History records the result either way.

If the relay stays unconfirmed, or you get “still reports … after the command”:

1. Check that the relay board has power.
2. Press “Signal” on the relay's page and check that a gateway has heard it recently; see Gateways in the app.
3. Look at Relay History. A result of “Didn't switch” means the board answered and kept its old state.
4. Try the command once more. If it fails again, contact support.

The “Relay History” card lists what happened to the relay, newest first, with the time to the second. The buttons at the top of the page choose the period: “Today Only” (selected when the page opens), “Last 24 Hours”, “Last 48 Hours” and “Last 72 Hours”. The longest you can look back is 72 hours.

The “Event” column has three kinds of row:

• “Device reported a change”: the board reported that a relay changed state. The Relay 1 and Relay 2 columns show both states after the change, and the relay that changed has a filled label.
• “Relay 1 → 🟢 ON”: a command sent from the relay's page; a pulse reads “Relay 1 → 🟢 ON for 300 s”. Under it are “Requested by” and the person's name. That relay's column shows the state the board reported in answer; the other relay's column shows a dash.
• “Status report requested”: CropWatch asked the board to report because an answer was late. These rows appear by themselves while a command is waiting.

“No relay changes or commands in this period.” means nothing happened in the chosen period; pick a longer one to look further back. If the history cannot be fetched, a red message says “Unable to load relay history for the selected range.”

Your permission level on the relay board decides what you can do. The levels are explained in The six levels.

• Owner, Admin and Manager: see everything on the relay's page and use every button.
• User and Viewer: see the same states and history, but the buttons and the duration box are greyed out, and a note reads “You need manager access or higher to queue relay commands.”
• Disabled: cannot see the relay board at all.

CropWatch checks the level again when each command arrives. If someone lowers your level while you have the page open, pressing a button answers “You do not have permission to control this relay” and nothing is sent.

An alert rule can switch a relay as well as, or instead of, telling a person: start a fan when the temperature passes 30 °C, for example. In the rule's “4. Alert Actions” card, set “Action Type” to “LoRaWAN”. The rest of the rule is set up as described in Creating an alert rule.

The action then asks for:

• “Device”: the relay board to switch. The list holds every sensor you have access to, each shown as its name and DevEUI, so pick the relay board by name.
• “Action”: “Relay 1 ON for 5 seconds”, “Relay 2 ON for 5 seconds” or “Both relays ON for 5 seconds” (the number follows the box below), or “Relay 1 permanently ON”, “Relay 1 permanently OFF”, “Relay 2 permanently ON” or “Relay 2 permanently OFF”.
• “On time in seconds”: shown for the timed actions only, from 1 to 86400 (24 hours).

The tick box “Revert relay state when the rule resets” can only be ticked with the four permanently ON or OFF actions. When the rule resets with the box ticked, CropWatch sends the board one command that switches both relays off. It does not put each relay back the way it was:

• With “Relay 1 permanently ON”, Relay 1 goes off at reset, and so does Relay 2 if it was on.
• With a permanently OFF action, the reset does not turn the relay back on; it switches both relays off.

While a timed switch-on sent by a rule is still running, CropWatch sends that board no other rule command. It waits until the time is up, plus a few seconds.

Some of these messages come from CropWatch's server and are always in English, whatever language you use the app in.

• I pressed Turn On and nothing seems to have happened. Look at the card. “Pending confirmation” means CropWatch is waiting for the board; give it up to a minute.
• All the buttons are grey. Either a command is still waiting for an answer (up to 60 seconds), or your level is below Manager, in which case a note under the controls says so.
• Turn On is grey, but I know the relay is off. CropWatch's latest report says it is on. Wait for the board's next report, or check Relay History for the last change.
• The dashboard still says Off after I turned the relay on. The dashboard follows the board's reports. Open the relay's page to see whether the command has been confirmed.
• Who switched this relay? Relay History shows “Requested by” and a name under each command sent from the relay's page. Changes made by alert rules show as “Device reported a change”.
• Why will the pulse not accept 10 seconds? The shortest pulse is 15 seconds.
• Can I see what happened last week? Not on this page. Relay History goes back at most 72 hours.