To define a trigger that executes when a CTI unsolicited message is sent, follow the steps for defining a new trigger. For more information on defining projects and triggers, see Defining a trigger
Every trigger identifies the trigger event type, which identifies when the trigger will be executed.
The PLC Logic Events category will list the available event types, based on the drivers that are installed on the node. The CTI driver supports the receipt of an unsolicited messages from CTI 2500 series programable controllers. The unsolicited message type that is currently supported is the Write Data message.
CTI 2572 Message event type trigger
To define a trigger that executes when a CTI unsolicited
message is received, select the CTI 2572
Message trigger event type.
The Event tab becomes active with
parameters that accommodate the event type. 
CTI 2572 Message trigger parameters
| Parameter | Description |
|---|---|
| Command | A filter that defines the messages this trigger will process. Select either Write Data to limit the trigger to process only messages of that type. Select All Commands to allow the trigger to process messages, regardless of the command code within the message. |
| Address | A filter that defines the acceptable message Address value that the trigger will process. A non-zero value in this field will limit the messages the trigger processes to only those messages that have a matching Address value. A value of 0 indicates that the Address filter is not to be used, so that all messages will be processed, regardless of the Address value. |
CTI 2572 Message event type trigger event variables
When a CTI 2572 Message event type trigger executes, controller data associated with the message is available as trigger event variables. The trigger event input variables are available to trigger actions that have input or source parameters are:
| Event Variable | Data type | Description |
|---|---|---|
| Address | UINT4 | The address value defined in the message. |
| IP Address | STRING | The IP address of the CTI 2500 series programmable controller that sent the message. |
| Message Data | Array of UINT2 | This is the data sent from the CTI controller. The data is represented as an array of up to a maximum of 256 UINT2 items. |
| Time | Timestamp | The date and time that the message was received by the CTI 2572 Listener device. |
| Word Count | UINT2 | The actual number of Words (UINT2)
items in the message. The maximum
number that can be in the message is
256.
This value will be used to process the Message Data array. This value, minus 1, will represent the last element in the Message Data array that contains data. |
The ladder logic on the controller that sent the message is expecting an integer code to be returned that indicates the status of the trigger execution. The developer of the ladder logic should be consulted to determine the range of values that are acceptable to be returned. Typically a value of 0 indicates the trigger was successfully executed. The trigger event output variable that is available to trigger actions that have output parameters is:
| Event Variable | Data type | Description |
|---|---|---|
| Response Status | INT4 | The value to be returned to the CTI controller. |