Set up System Variables

Scope

A system variable is a named value on the logger that Smart Alerts, Plant Control and the System Variables widget read. For each field, see System variables field definitions.

Location

• Path: My Devices, the logger, then the System Variables tab.
• Menus: the three-dot icons on the table header and on each row open the menus.

Permissions

• See the variables: any access level.
• Add, change and delete user and computed variables: Editor, Installer or Full control.
• Change and remove device data points: Editor, Installer or Full control.

Step 1: User Variable

1. On the User sub-tab, in the table menu, click Add Row.
2. In the new row, named changeme, type the Name.
3. Select the Ui Comp Type.
4. Select the Value Type.
5. Set the Value.
6. Click the save icon of the row.

Step 2: Drop Down Options

1. In the row menu, click Edit Options.
2. Click the plus icon.
3. Type the Value and the Name of the option.
4. Click the save icon of the dialog.

Step 3: Device Data Point

1. On the DDP (device data points) sub-tab, in the table menu, click Add DDP.
2. In Search All fields, type part of the field name.
3. In the row menu of the field, click Add.

Step 4: Computed Variable

1. On the Computed sub-tab, in the table menu, click Add Row.
2. Type a name in the Name field.
3. In the Formula field, type numbers and operators.
4. To add a live value, type {.
5. Click a value in the list.
6. Check the result line under the field.
7. Click Create variable.

Troubleshooting

• Name is required: type a name for the variable.
• Computed variables cannot reference each other: use the formula of that variable in its place.
• Formula result is not a number (division by zero?). A divisor is zero. Change the formula.
• Device offline for System Variable [id]: make sure that the device is online.

Tips and Gotchas

• The Value columns show the values from when the page loaded. Reload the page to see new values.
• Plant and Digital IO values have no sub-tab of their own. They show only in the formula value list.
• A formula or a Smart Alert that uses a deleted variable gets no value.
• An MQTT client can set the value of a user variable. The LoggerV does not check a myPower24 access level for this change. See Set up the MQTT client.