Real-Time Workshop

External Signal & Triggering Dialog Box

Clicking the Signal & triggering button activates the External Signal & Triggering dialog box.

Figure 6-7: Default Settings of the External Signal & Triggering Dialog Box

The External Signal & Triggering dialog box displays a list of all blocks and subsystems in your model that support external mode signal uploading. See External Mode Compatible Blocks and Subsystems for information on which types of blocks are external mode compatible.

The External Signal & Triggering dialog box lets you select which signals are collected from the target system and viewed in external mode. It also lets you select a signal that triggers uploading of data when certain signal conditions are met, and define the triggering conditions.

Default Operation

Figure 6-7 shows the default settings of the External Signal and Triggering dialog box. The default operation of the External Signal and Triggering dialog box is designed to simplify monitoring the target program. If you use the default settings, you do not need to preconfigure signals and triggers. Simply start the target program and connect the Simulink model to it. All external mode compatible blocks will be selected and the trigger will be armed. Signal uploading will begin immediately upon connection to the target program.

The default configuration is:

• Arm when connect to target: on
• Trigger Mode: normal
• Trigger Source: manual
• Select all: on

Signal Selection

All external mode compatible blocks in your model appear in the Signal selection list of the External Signal & Triggering dialog box. You use this list to select signals to be viewed. An X appears to the left of each selected block's name.

The Select all check box selects all signals. By default, Select all is on.

If Select all is off, you can select or deselect individual signals using the on and off radio buttons. To select a signal, click on the desired list entry and click the on radio button. To deselect a signal, click on the desired list entry and click the off radio button. Alternatively, you can double-click a signal in the list to toggle between selection and deselection.

The Clear all button deselects all signals.

Trigger Options

The Trigger panel located at the bottom left of the External Signal & Triggering dialog box contains options that control when and how signal data is collected (uploaded) from the target system. These options are:

• Source: manual or signal. Selecting manual directs external mode to start logging data when the Arm trigger button on the External Mode Control Panel is clicked.

• Selecting signal tells external mode to start logging data when a selected trigger signal satisfies trigger conditions specified in the Trigger signal panel. When the trigger conditions are satisfied (that is, the signal crosses the trigger level in the specified direction) a trigger event occurs. If the trigger is armed, external mode monitors for the occurrence of a trigger event. When a trigger event occurs, data logging begins.

• Arm when connect to target: If this option is selected, external mode arms the trigger automatically when Simulink has connected to the target. If the trigger source is manual, uploading begins immediately. If the trigger mode is signal, monitoring of the trigger signal begins immediately, and uploading begins upon the occurrence of a trigger event.

• If Arm when connect to target is not selected, you must manually arm the trigger by clicking the Arm trigger button in the External Mode Control Panel.

• Duration: The number of base rate steps for which external mode logs data after a trigger event. For example, if the fastest rate in the model is 1 second and a signal sampled at 1 Hz is being logged for a duration of 10 seconds, then external mode will collect 10 samples. If a signal sampled at 2 Hz is logged, only 5 samples will be collected.
• Mode: normal or one-shot. In normal mode, external mode automatically rearms the trigger after each trigger event. In one-shot mode, external mode collects only one buffer of data each time you arm the trigger. See Data Archiving Dialog Box for further details on the effect of the Mode setting.
• Delay: The delay represents the amount of time that elapses between a trigger occurrence and the start of data collection. The delay is expressed in base rate steps, and can be positive or negative. A negative delay corresponds to pretriggering. When the delay is negative, data from the time preceding the trigger is collected and uploaded.

Trigger Signal Selection

You can designate one signal as a trigger signal. To select a trigger signal, select signal from the Trigger Source menu. This activates the Trigger signal panel (see Figure 6-8). Then, click on the desired entry in the Signal selection list, and click the Trigger signal button.

When a signal is selected as a trigger, a T appears to the left of the block's name in the Signal selection list. In Figure 6-8, the Pilot G force Scope signal is the trigger. Pilot G force Scope is also selected for viewing, as indicated by the X to the left of the block name.

Figure 6-8: Signals & Triggering Window with Trigger Selected

After selecting the trigger signal, you can define the trigger conditions in the Trigger signal panel, and set the Port and Element fields located on the right side of the Trigger panel.

Setting Trigger Conditions

Note    The Trigger signal panel and the Port and Element fields of the External Signal & Trigger dialog box are enabled only when Trigger source is set to signal.

By default, any element of the first input port of the specified trigger block can cause the trigger to fire (i.e., Port 1, any element). You can modify this behavior by adjusting the Port and Element fields located on the right side of the Trigger panel. The Port field accepts a number or the keyword last. The Element field accepts a number or the keywords any and last.

The Trigger Signal panel defines the conditions under which a trigger event will occur. These are:

• Level: Specifies a threshold value. The trigger signal must cross this value in a designated direction to fire the trigger. By default, the level is 0.
• Direction: rising, falling, or either. This specifies the direction in which the signal must be travelling when it crosses the threshold value. The default is rising.
• Hold-off: Applies only to normal mode. Expressed in base rate steps, Hold-off is the time between the termination of one trigger event and the rearming of the trigger.

Target Interface Dialog Box

Data Archiving Dialog Box