Capture Type Function Block

Overview

Capture type function blocks (commonly refered to as capture blocks) allow the ability to catch data as it comes over the network and save it to a buffer file for future analysis. A host of options and parameters split across multiple tabs allow the function block to be tailored to any use case. These blocks allow anything from a simple manual capture of a small amount of data, to sophisticated setups that record precise message sets based on custom filtering and trigger logic.

Applications

Table 1 describes just a few of the many ways that capture blocks can be used. In each case the application is described and a brief summary is provided of the capture block settings that might be used in a setup; these are presented in the same order that capture block tabs appear. Of course these are only samples and settings can be combined in almost any way that is required.

Table 1: Sample applications of capture type function blocks

Application Description	Buffer	Start Type	Stop and Trigger Options	Storage
Save current data in a large, unfiltered buffer, possibly triggered by a hotkey.	No filtering	Start Immediately	Collect in a circular buffer, with large buffer	Manual save
Save a new buffer file at a periodic rate. (Warning: This can fill up storage if set up incorrectly!)	No filtering	Start Immediately	Collect in a circular buffer, with very large buffer	Save when expression is true
Create a small, filtered buffer file, triggered by a joystick button.	Filtering	Manual Start	Collect in a one-shot buffer, with small buffer	Automatically save when complete
Capture data before and after a hotkey click.	Filtering	Start Immediately	Collect before and after a manual trigger, with small buffer and large post-trigger buffer	Automatically save when complete
Store a large amount of data before an event that occurs very quickly.	No filtering	Start Immediately	Collect before and after a trigger expression, with large buffer and small post-trigger buffer	Automatically save when complete
Capture data that occurs between two events.	Filtering	Use Start Expression	Collect in a circular buffer, with large buffer	Save when expression is true
Capture data filtered using a script, with start, trigger and save expressions for ultimate flexibility.	Filtering using script	Use Start Expression	Collect before and after a trigger expression, with mid-sized buffer and post-trigger buffer	Save when expression is true

Creating a Capture Block

Create a new capture block by clicking the button on the far left of the function block toolbar and then select Capture from the popup menu. Vehicle Spy will create a default capture block as shown in Figure 1, with the Filter Tab selected.

Figure 1: Default capture block setup.

Renaming a Capture Block

Like all function blocks, a new capture block will appear in the function block list near the top of the function block pane. The function blocks can be renamed by double-clicking on the default name (Function Block 1) and entering a more descriptive name.

The name entered in the function block list also appears in blue in the function block setup area for greater clarity.

Capture Block Tabs

As shown in Figure 1, capture type function blocks have their parameters divided into five tabs. The following is a brief description of these tabs with links to pages covering each in more detail:

Filter Tab: Allows you to specify filters to restrict which messages are captured by the block.
Start Tab: This tab is common to all function block types and allows you to specify the block's Start Type and related options.
Stop and Trigger: In this tab you tell Vehicle Spy how much data to capture and how to capture it.
Storage: Here you decide when to save the captured data and what formats and options to use.
Data: This is a read-only tab where you can view messages as they are being captured.