Control registers from the portal

Control is off by default on every gateway. Only ModbusCloud turns it on, per gateway and on request. After that you write values from the gateway page, with a control widget on a dashboard or with an automation.

What you need

• The role Owner, Admin or Technician in your organisation.
• At least one register with Toegang (access) set to Lezen + schrijven (read and write). Without such a register the gateway page has no Control tab. A template can already include one. To set it yourself, see Set up registers.
• A gateway with the status Online for writing.

Request control

Loading the walkthrough.

After these steps the request is with ModbusCloud. It applies to the whole gateway, so to all writable registers on it.

1. Open the gateway list

   Open Gateways in the menu.

2. Open the gateway

   Click the gateway.

3. Choose the tab

   Choose the Control tab. Above the registers it says Control is off for this gateway.

4. Request control

   Click Request. The message changes to Control has been requested. You'll get an email once it's on.

If there is no message above the registers, control is already on. While control is off, you cannot select the registers on the tab and the portal sends nothing to the gateway. Once ModbusCloud turns control on, whoever clicked Request gets an email with the button Open gateway. The message on the tab then disappears.

If the portal reports that requesting failed, email the address in the message. To turn control off again later, ask through the support page.

Write a value

Each writable register appears as a card on the Control tab, per Modbus device and with the last value read. If there are more than six, a filter on name or address appears above them.

1. Open the gateway

   Open the gateway.

2. Choose the tab

   Choose the Control tab.

3. Choose a register

   Click the card of the register. The window Write register opens with the Current value.

4. Enter the value

   In New value, enter the value. If the register has fixed states, choose a state from the list.

5. Check the value

   Click Next. The window asks you to confirm the value.

6. Retype the name

   If the register shows Critical, type the exact name of the register in the field.

7. Send the value

   Click Confirm & send. As soon as the Modbus device has accepted the value, the window shows Done.

8. Close the window

   Click Close. The card shows Just sent until the gateway has read the register again.

Enter the value as the portal shows it, so with the scale applied. If Schaal (x) (scale) is 0.1 and you enter 21.5, the gateway writes 215 to the register. If the register has a minimum and a maximum, the range appears under the field. The portal does not send a value outside it.

If the gateway is not Online, the text Gateway is offline, write not possible appears above the cards and you cannot select the cards.

View written values

Below the cards is the Command history with the last 50 write commands to this gateway, including those from widgets and automations. Users with read-only access see only this list on the Control tab.

The table shows what each column contains.

Export CSV above the list downloads it as a CSV file.

Messages when writing

If writing fails, the window shows a message instead of Done. For an error from the gateway or the Modbus device, a short technical text appears below it. Send it along when you get help.

The table shows the cause of each message and what to do.

Over RS485 the gateway writes holding registers with function code 6 and 16, and no coils. To a Modbus TCP device it writes one 16-bit holding register or one coil per command.

The portal accepts at most 20 write commands per minute per user, and at most 30 per gateway.

Write with widgets and automations

Control widgets and automations write to a register only if control is on for the gateway.

The widgets Switch, Button, Manual input and Slider on a dashboard write to a register. If control is off, Control off appears in the corner of the widget. How you place them is in Create a dashboard.

An automation can write a register as an action. If control is off, the rule skips that action. A message then appears below the action, with the button Request as long as nobody has requested control. How you set up the action is in Create automations.