> For the complete documentation index, see [llms.txt](https://docs.intrepidcs.com/vehicle-spy-quick-start-guides-using-vspy-ethernet/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.intrepidcs.com/vehicle-spy-quick-start-guides-using-vspy-ethernet/4-simulating-and-reviewing-ethernet-message-files.md). # 4 - Simulating and Reviewing Ethernet Message Files Once you have saved Ethernet data to a file, you have several options for working with it. Two of the most important are *simulating* the file and *reviewing* it, which we’ll show you how to do in this chapter. Note that this part of the guide assumes that you saved a buffer of Ethernet data in Section 3.9. If you have not done this yet, please review the relevant parts of Chapter 3 and save an Ethernet buffer before proceeding here. #### 4.1 Simulating an Ethernet Data File Simulating a data file is an alternative to going online with a live network. Vehicle Spy will replay the file, causing its messages to appear in *Messages View* in the same order, and with the same timing, as occurred on the network when they were captured. This is a useful tool for diagnosing problems, since you can repeat a message exchange in the same way multiple times. You can also control the speed of the simulation, slowing it down for easier observation. If you’ve simulated a file in Vehicle Spy before, the process is pretty much the same for Ethernet data files. ► **Browse to Data Directory:** Click the down-arrow next to the ![](https://2434793200-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FeOxMUhoKSgToToWJ42dE%2Fuploads%2FGh5hVKXGaqaWtrAAm3JL%2Fimage-025.jpg?alt=media\&token=323eb1a6-1359-4a5b-82c8-817ecd6e2335) button, hover the mouse over *Run Simulation*, and when the submenu appears, select *Browse*... (Figure 24).

Figure 24: Browsing to a Simulation File.

A Windows file selection box will now appear opened on your data directory. ► **Select a Simulation File:** Click the file you want to simulate (probably the one you saved earlier in the guide), then click the

button. Assuming that a valid file was selected, Vehicle Spy will begin playing back its messages within Messages View. The screen will appear quite similar to how it did when going online live, except that you will notice the simulation bar at the top, which shows you VSpy’s progress as it goes through the file (Figure 25). The current speed of the simulation is shown in the bar (in the figure it says “speed: 1.00x”). You can change this by moving the adjacent speed slider left or right, selecting a speed from 0.01x to 20x.

Figure 25: Simulating an Ethernet Data File.

By default, the simulation will continuously loop through the file. You can turn this off by clicking ![](https://2434793200-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FeOxMUhoKSgToToWJ42dE%2Fuploads%2Fvd8yPBKbqdl5fvjM8Zz8%2Fimage-056.png?alt=media\&token=58e6ee54-6682-4ddb-beb3-69a496e595bc) the button. You stop the simulation by going offline. ► Go Offline: Press the ![](https://2434793200-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FeOxMUhoKSgToToWJ42dE%2Fuploads%2FBMjkwlXjsXP107HEkBbH%2Fimage-057.jpg?alt=media\&token=9f4ff84e-f430-4242-9290-a597c89feabf) button. #### 4.2 Reviewing an Ethernet Data File Reviewing a file is used most often to simply look at what messages it contains. You choose the file and the messages are shown in the order they were stored with the same timestamps. Again, this process is pretty much the same for Ethernet data as it is for other networks. Let’s try an example. ► **Tell Vehicle Spy to Review a File:** Choose *Review Buffer...* from the *File* menu. ► **Select a File:** When the Windows file selection dialog appears, select a file from your data directory. Vehicle Spy will now present a dialog box allowing you to choose what platform you want to use and whether you want to load the file in standard or streaming mode. Again, this is identical to what happens when reviewing a .VSB file with CAN or other network data. In most cases we can leave these options at their default settings. ► Proceed with File Review: Click the ![](https://2434793200-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FeOxMUhoKSgToToWJ42dE%2Fuploads%2FGdzYJYWmTq6Q4r1SNxrP%2Fimage-058.png?alt=media\&token=a056bfe8-77fb-436c-8b9f-5f2c9ee8b74f) button. Vehicle Spy will load the buffer file, stopping with the last message showed at the bottom of the *Messages View* display. --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation by asking a question. Perform an HTTP GET request on the following URL with the `ask` and `goal` query parameters: ``` GET https://docs.intrepidcs.com/vehicle-spy-quick-start-guides-using-vspy-ethernet/4-simulating-and-reviewing-ethernet-message-files.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is what the user is ultimately trying to achieve, the reason they need the answer. Sharing it helps GitBook give you a better, more relevant answer. A goal is most helpful when it describes the outcome the user wants rather than restating the question. For example, with `ask=how do I create an API token`, a goal like `automate deployments from our CI pipeline` lets GitBook tailor the answer to that use case. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.