If you want users to be able to trigger actions remotely by using SMS, we recommend that you configure your system to make use of the alias feature on Method Call database items. The alias feature allows you to associate a string of up to 32 characters with the action and database defined in the Method Call’s configuration. Remote users with appropriate permissions can then trigger the Method Call’s action by entering the alias string as the content of their SMS. There are several benefits to using aliases when sending SMS commands:
- Convenience
- Increased Reliability
- Reduced Cost
It is much quicker to issue an SMS command when using an alias. This is because an alias can only be up to 32 characters, whereas a full reference to an action can be considerably longer and may even span multiple SMS messages.
As an alias is only 32 characters or less, there is also less likelihood of a user making an error when entering the content of the SMS message.
If an alias is used, the SMS command is a single SMS message. This means ClearSCADA can trigger the appropriate action as soon as ClearSCADA receives and processes the SMS message. As the SMS command is a single message, the potential for delays is reduced, as ClearSCADA only needs to receive one SMS message for the command as opposed to multiple messages which can be the case when aliases are not used.
If an alias is not used, the reference to trigger a remote action may exceed the length of a single SMS message. In this situation, the reference will be sent in multiple messages (referred to as a multi-part message). This has the potential to cause problems as the SMS service provider may not send all parts of the multi-part message within a suitable time frame (1 hour), for example, during times of heavy network traffic, there may be delays between each part of the multi-part message being sent. As ClearSCADA can only process the SMS command when it receives all parts of a multi-part message, any delays at the service provider will also mean there are delays between the SMS being sent and the action being executed in ClearSCADA. If all parts of a multi-part SMS message have not arrived within 1 hour, the message is disregarded by ClearSCADA (and a record of the incomplete message is logged in the Pager Driver log).
As an SMS command that uses an alias can only be a single SMS message, the cost of sending that command is the cost of sending 1 SMS message. If an alias is not used, an SMS command can span multiple messages, with the total cost of sending the SMS command being the cost of sending each part of the message.
To issue an SMS command by using an alias, the following configuration has to be in place:
- An SMS Service has to be In Service and configured to define the appropriate message settings such as Maximum Message Length, number of Retries and the Timeout
- An SMS Pager Channel has to be In Service and configured to have the appropriate settings for the ClearSCADA-service provider connection
- Your user account has to have the appropriate Pager ID for the device you are going to use to send the SMS. It also needs to be associated with the appropriate SMS Pager Service and have SMS Commands enabled
- Your user account needs the appropriate permission for the database item (that has the action that is to be triggered). The permission required will vary according to the action you are attempting to trigger. For example, if you are using SMS to acknowledge an alarm for a point, your user account needs the Acknowledge Alarms permission for that specific point, whereas if you are using SMS to Hand Control a point, your user account will need to have the Control permission for the point.
- A Method Call item has to be configured to reference the appropriate database item and action for your requirements. If there are parameters for the action, these also need to be defined in an expression in the Method Call item’s configuration. The Method Call configuration should also define the alias that you need to use when sending the SMS command.
For more information on the User Form’s Contact Information properties, see Define the E-Mail, Pager, and Voicemail Contact Settings for a User in the ClearSCADA Guide to Security.
For more information on permissions, see Permissions for Database Items in the ClearSCADA Guide to Security.
For more information on the Method Call configuration, see Configure the Method Call’s Properties in the ClearSCADA Guide to Core Configuration.
With the settings described above in place, you can trigger an action remotely via SMS:
- On the appropriate device, create a new SMS message.
- For the content of the SMS message, enter the alias. The alias is case sensitive and you the SMS message can only contain the alias string. Do not include any other string or character other than the alias in your SMS message as this will cause the SMS message to be disregarded by ClearSCADA (unless the alias and the characters you have added matches an action for the Root group item, in which case, that action will be triggered erroneously. That is why we strongly advise you to use aliases that are unique and not similar to existing actions for the Root group.
- Send the message to ClearSCADA.
The message will be processed by the service provider and will be sent to ClearSCADA. ClearSCADA will then process the message and execute the action associated with the Method Call that has the alias that matches the alias in your SMS message.
NOTE: There may be a delay between sending the message and the required action being triggered. The length of the delay is dependent on how long it takes the service provider to process and send the message to ClearSCADA. In many circumstances, the action you wish to trigger with your SMS command will be performed seconds after you send your SMS message.