SMS Appliance Tags

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The SMS Appliance tag works in conjunction with the Alarm Notification System option to allow alarm notifications to be sent as text messages to a mobile cellular device, and to allow alarm acknowledgment via SMS.

SMS messages are sent and received using an "SMS appliance," which is a cell phone (or "cell modem") tethered to a VTScada workstation via RS-232, Bluetooth, or USB. Any such "cell modem" should conform to ETSI TS 100 585, which is a part of the GSM standard applying to the AT command set for sending and receiving text messages. Devices that use the CDMA standard are not supported.

The SMS Appliance tag handles communications through the SMS appliance. The tag registers with the SMS Manager service as an SMS agent.

Since SMS appliances are usually installed as "modems" under MS Windows™, the configuration of the SMS Appliance tag enables the specification of this modem and the workstation to which the modem is attached. You may also set a security privilege, and if necessary, can mark the modem as disabled.

If running multiple applications (for example, hosted systems) modems, SMS devices, and Twilio accounts cannot be shared between applications. You must have independent modems or Twilio accounts for each application.

The SMS Manager takes care of forwarding message requests to any registered SMS agents in a round-robin sequence. It also provides a publisher for received SMS text messages. Code that subscribes to received messages will get notification of all received text messages. Subscribers are responsible for any filtering of received text messages.

The SMS Appliance tag will re-initialize the appliance once per minute to verify that it is still attached and functioning. Any error will result in a complete reset, which is repeated at a regular interval until the tag is disabled or a functioning device is available.

The SMS Appliance tag will queue messages to send, so long as it is operating normally. Received messages are published immediately. If these should be queued, it is the responsibility of the subscriber to do so.

The value of the SMS Appliance tag can be used to monitor the device status, according to the following table. (These values are reflected in the SMS Indicator widget.)




Connected to cell modem


Sending an SMS Message


Receiving an SMS message


Checking the connection to the cell modem




Workstation with modem is not available


Modem unavailable

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