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Software Documentation - v1.40
wOBD Poll Designer Screen
Last updated August 27, 2004

Summary   Menu Items   Field Descriptions

Summary The polling designer screen allows a great deal of flexibility in controlling what data is gathered, when it is gathered, and how it is displayed. New Polling Designs The first time the program is run, or if the previous design was not saved or is not available, a new polling design is displayed. (see top screen shot) A new polling design can also be started by pressing the lower New button, pressing alt-N, or via the File menu. New polling designs contain the first 31 generic OBD2 data codes. Codes that return bitmap values, and codes that are unlikely to change have their Poll Frequency set to 0 (disabled). Disabled codes are shaded gray. By default, active codes are set to a Poll Frequency of 10, which indicates they will be polled every 10th loop. The offset indicates which of the 10 loops the code will be polled at. By default the codes are spread out among 10 loops. To see exactly how they will be spread out, use the Timeline tool. See calc offset example Verify Polling Design Against Supported Codes The polling design above can be optimized further by removing codes that your vehicle does not support. If your vehicle is currently connected via the OBD2 connector, we can try and do this automatically via a standard OBD supported functions code (0100). Of course, some manufacturers don't do a perfect job implementing this feature, but under the right conditions it will disable (set Polling Frequency to 0) the codes that will only generate errors during polling. Since this usually eliminates 8 or 9 codes, you will probably want to use Calc Offset again to rebalance the loops. Grouping Codes If you are going to compare code values against each other, you can get more relevant comparisons by collecting data from the related codes at the same time. Although it is not possible to get the code results at exactly the same time, you can get pretty close by grouping the related codes into the same loop. SImply make sure that the codes all have the same Poll Frequency and offset values. Use the Timeline tool to make sure the loops are as you expected. A good example is when a comparison of the O2 sensors is done to check catalytic converter efficiency. Since the O2 sensors output a rapidly fluctuating voltage, it would be easy to be misled if these values were compared after being collected a few seconds apart. For a more thorough treatment of sampling timing when using the ELM chipset OBD2 converters, be sure to check our OBD2 tech info pages for the ELM data sampling rate topic. To rearrange codes within a group, use the drag and drop feature on the code value. For example, to monitor O2 Sensor 1-7 Voltage and O2 Sensor 1-3 Voltage (in that order), make sure they both have the same Polling Frequency and offset values, and then drag the O2 Sensor 1-7 Voltage code and drop it so that it precedes the O2 Sesor 1-3 Voltage code. Collecting Some Codes More Frequently Than Others Often you will want to monitor a code more closely than the rest, or you want to more frequently sample a code that changes quickly. (or sample less frequently a slow to change value) To do this, assign your more rapidly changing codes a lower Polling Frequency. In example, to monitor RPM on every loop, set its Polling Frequency to 1. Be sure and use the Timeline tool to see how this effects polling. Using Non-Generic Codes If you are lucky enough to know some of the manufacturer specific codes, or if you have discovered extended generic codes that are supported by your vehicle, you can add them to the polling design using the Add New Event (ctrl-A) under the Edit menu. If your codes require a non-standard header, use the Add Init tool to specify commands that will be sent before polling starts. (see the Scanner page for more information about extended codes and setting a physical address header) Note that you cannot specify generic codes and codes that require a special header on the same polling design. Other Uses of the Add Init Tool In addition to specifying a non-standard header as mentioned above, the Add Init can also influence sampling rate as described by our OBD2 tech info pages for the ELM data sampling rate topic. Be sure not to specify the reset (ATZ or ATD) or modify echo (ATE0) as this will affect the ability of the polling process to collect data.

Menu Items

Field Descriptions

• Title text - title to be used when printing and saving; displayed during polling
• Polling Screen button - (alt-P) finished with the design, go to the polling screen
• Exit to Main Menu button - (alt-X) will close com (if necessary) and return to main menu (same as ctrl-q)

• Code hexadecimal - hexadecimal command sent to OBD2 describing data point requested. Drag and drop feature is implemented on this field to enable manual re-arranging the codes.
• Code Description text - Description of code, used as a label and displayed during polling
• Unit Conversion choice list - describes any unit conversions to be performed on the data when displaying
• Poll Frequency numeric - the modula of the loop index to schedule the event in the polling loops. The lower the number, the more often polled. In example, 1 - event polled every loop, 2 polled every other loop, 3 every 3rd loop,etc. The exact timing in seconds is variable (see our OBD2 tech info pages for the ELM data sampling rate topic) For discussion purposes, we are assuming the events occur about 280ms apart, a little under 4 events per second. For an example, refer to the summary section above.
• Offset numeric - Added to poll index before calculating modula. Used to formalize grouping of events when polling occurs. In example, if 3 events have a poll frequency of 2, the offsets 0 and 1 may be used to group any of the events into the first loop or the second loop. Offsets greater than the poll frequency are simply treated as equal to (offset modula poll-frequency). In this way, precise control of polling events can be achieved. To view the current polling events by loop, use the Timeline tool. For an example, refer to the summary section above.

• Save button - (alt-S) Saves poll setup to a text file
• Open button - (alt-O) Retrieves poll setup saved in text file
• Print button - (alt-P) Print Poll Setup
• New button - (alt-N) Uses the default generic OBD2 codes 01-1f
• Disable button - (alt-D) Disable all events by setting poll frequency to 0
• Add Init button - (alt-I) Add a command to be sent to OBD2 converter before polling starts
• Verify button - (alt-V) Disable codes that are not supported by vehicle
• Timeline button - (alt-T) List polling loops and codes that are scheduled in each
• Calc Offset button - (alt-C) Distribute codes with same frequency evenly across polling loops. See calc offset example

• Status Description text - displays any messages, and the number of bytes transferred while using this screen.

Calc Offset Example