Defining a trigger for a Siemens (AG_SEND/TSEND) unsolicited message

To define a trigger that executes when a Siemens unsolicited message is sent, follow the steps for defining a new trigger.
For complete 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 Siemens driver supports the receipt of AG_SEND and TSEND unsolicited messages sent from Siemens PLCs. The Siemens (AG_SEND/TSEND) event type will support the receipt of the two message types sent to a S7 Listener device that is defined with the ISO on TCP Protocol value.

Siemens (AG_SEND/TSEND) event type trigger

To define a trigger that executes when a Siemens AG_SEND or a Siemens TSEND unsolicited message is received on the ISO on TCP port (102), select the Siemens (AG_SEND/TSEND) trigger event type. The Event tab becomes active with parameters that accommodate the event type.

Siemens (AG_SEND/TSEND) trigger parameters

Parameter	Description
Device Name	A list of all of the Siemens S7 Listener devices that have been defined on the node. The S7 Listener devices that process the AG_SEND and TSEND message must have a Protocol value of ISO on TCP. For information about the S7 Listener device type and the Protocol parameter, see Using the Workbench to define a Siemens S7 Listener device.
Filter	Specifies the received messages that will execute the trigger. The options are: None: This is the default option. When selected, any AG_SEND or TSEND message received by the S7 Listener device selected in the Device Name parameter will execute the trigger. TSAP (ASCII): This option allows the trigger to execute based upon the TSAP values obtained when a Siemens PLC connects to the S7 Listener device. The maximum length of the values entered in the source and destination parameters is eight characters. Either one of the parameters may be left blank, but the trigger cannot be saved if both of the parameters are left blank. Blank parameters will be ignored when filtering messages received by the S7 Listener.
Source TSAP (ASCII)	This parameter is displayed if the TSAP (ASCII) value is selected in the Filter parameter. The value of the Source TSAP that was specified in the connection logic on the Siemens PLC will be entered into this parameter to filter on the Source TSAP value. This TSAP value is sent to the S7 Listener device when the PLC connects to the node. A value is required in this parameter if the Destination TSAP (ASCII) parameter is left blank.
Destination TSAP (ASCII)	This parameter is displayed if theTSAP (ASCII)value is selected in theFilterparameter. The value of the Destination TSAP that was specified in the connection logic on the Siemens PLC will be entered into this parameter to filter on the Destination TSAP value. This TSAP value is sent to the S7 Listener device when the PLC connects to the node. A value is required in this parameter if the Source TSAP (ASCII) parameter is left blank.

Siemens (AG_SEND/TSEND) event type trigger event variables

When a Siemens (AG_SEND/TSEND) event type trigger executes, PLC data associated with the message is available as trigger event variables. The trigger event variables that are available to trigger actions that have input or source parameters are listed below.

Event Variable	Data type	Description
Data	BINARY	This is the data from the Siemens PLC. It is sent by the ladder logic running on the PLC as part of the AG_SEND or TSEND message. The data type is binary, allowing the user to process it as a single data element, an array of elements of a specific data type, or a combination of different data types.
Data Length	INT4	The number of bytes in the data portion of the message.
Device Name	String, length 128 characters	The name of the S7 Listener device that received the message.
IP Address	String, length 32 characters	The IP address of the PLC that sent the AG_SEND or TSEND message.

There are no output event variables associated with this event.

Siemens (AG_SEND/TSEND) event type trigger runtime behavior

AG_SEND and TSEND messages are sent from a Siemens S7 PLC to a S7 Listener that is listening on the ISO on TCP port, which is port 102. Triggers that are using the Siemens (AG_SEND/TSEND) event type have the option of defining a filter. The filter is a valuable way to associate specific triggers with messages sent from a specific PLC. To begin communications with the S7 Listener device, the Siemens PLC will send a Connection Request message. Embedded within the Connection Request message are two parameters, the Source TSAP and the Destination TSAP. These values will be maintained by the S7 Listener and associated with each specific PLC Connection. The TSAP values received when the connection is made can then be used as a trigger filter when the S7 Listener receives a message on that connection. The TSAP parameters contain ASCII characters and are a maximum of eight characters in length.

A filter can be defined using both the Source and the Destination TSAP values, just the Source TSAP value, or only the Destination TSAP value. TSAP values that are blank will be ignored. At least one TSAP parameter must contain a value, if the TSAP (ASCII) filter is selected.

For example: Trigger A can be defined with a blank Source TSAP value and a Destination TSAP value of TS123, while Trigger B is defined to handle messages with a Source TSAP value of SRC678 and a blank Destination TSAP value. Finally a third trigger, Trigger C is defined with None selected in the Filter parameter. Trigger C's definition allows it to process every AG_SEND or TSEND message received by the S7 Listener, regardless of TSAP values associated with each connected PLC. AG_SEND or TSEND messages received from PLCs that connect with a Source TSAP value of SRC678 will be processed by Trigger B and Trigger C. AG_SEND or TSEND messages received from PLCs that connect with a Destination TSAP value of TS123 will be processed by Trigger A and Trigger C.