Although not the recommend technique for triggering an action via SMS, it is possible for you to trigger an action by referencing the Execute method of a Method Call. When ClearSCADA receives an SMS message that references a Method Call’s Execute method, it will perform the action that is defined in the configuration of the Method Call. For example, let’s say that a Method Call named ‘Point 1 MC’ is associated with the Override action of a point named ‘DBP’. A user then sends an SMS message that references the Execute method of the ‘Point 1 MC’ Method Call. ClearSCADA processes the message and performs the Override action on the ‘DBP’ point, as these are the action and database point associated with the ‘Point 1 MC’ Method Call.
When you reference the Execute action of a Method Call, you need to include the FullName value of the Method Call, which includes its parent Group(s) as well as its name. You also need to reference its Execute action. As Method Calls can be nested in your system’s hierarchy, this can mean that the FullName and Execute reference can exceed the maximum size limit for a single SMS message. If your reference exceeds the maximum limit for an SMS, the reference is sent in parts in several SMS messages (this is called a multi-part SMS message).
Multi-part SMS messages have disadvantages when compared to using a Method Call with an alias:
- They may consist of long strings that take longer to enter manually than an alias (which is a maximum of 32 characters).
- Multi-part messages can be unreliable as ClearSCADA has to receive each part of the message before it can perform the required action. If the service provider is experiencing problems such as heavy network traffic or the network going down, there is an increased likelihood of delays and ClearSCADA may have to wait for a significant amount of time to receive all parts of a message. In some circumstances, such as a network failure, parts of the message may be lost entirely or may not be received by ClearSCADA within the expected time range of 1 hour. If ClearSCADA receives part of a message and does not receive the remaining parts of the message within 1 hour, the message is disregarded.
- Increased cost. When an alias is used with a Method Call, the SMS command is one message (and so costs the price of sending a single SMS message). With a full reference to the Execute action of a Method Call, the SMS command may span several messages, with each part of the message costing the price of a single SMS message.
To issue an SMS Command by referencing the Execute action of a Method Call, 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 has to be associated with the appropriate SMS Pager Service and have SMS Commands enabled
- Your user account has to be configured to have 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 within the Method Call item’s configuration.
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 use a reference to a Method Call’s Execute method to trigger an action remotely via SMS:
- On the device that is associated with your user account, create a new SMS message.
- Enter the reference to the relevant Method Call’s Execute method as the content of your SMS message. The SMS message should only contain the characters for the reference and has to be in this format:
- Send the message to ClearSCADA.
When ClearSCADA receives your SMS message via the service provider, it determines which Method Call is referenced in the SMS message. It then executes the action that is defined in the Method Call’s configuration.
<Method Call Reference>.Execute()
Where:
<Method Call Reference> is the FullName value of the Method Call which includes all of its parent Group(s) as well as its name. Do not enter the angle brackets < >.