This section of the Prius Mini-Scanner User Manual discusses the options that can be set in Options mode.
This option sets the number of data items that will be requested from the vehicle. The default is two, so that the two data items selected into the current slot are requested and displayed. In Display mode, these are the items in the Display slot. In Favorites mode, these are the items in the current Favorite slot. Other choices for the option are from 3 up to 6. The additional data items requested are defined by the next sequential slot(s) to the current slot. For example, in Display mode the third requested item is the first from Favorite slot 1, the fourth is the second in Favorite slot 1, etc.
Normally, only the first two data items are displayed. (Four items would be displayed if the Display Method is set to Compress or if a 4-line display unit is installed.) However, if logging via the serial port is active, all requested items are logged. After the first two items in columns two and three of the log file, additional items appear in order in consecutive columns. For example, if the number of items is set to three, the third item will appear in column four.
The selected choice for this option is saved at power-down and will be effective at the next power-up.
The original design of the Mini-Scanner Mark I allowed only two data items to be displayed at the same time. There has been considerable pressure from users to display more items. The Mark II Mini-Scanner will meet this need but in the interim an alternate display method has been added to the Mark I. This option allows you to select between the "Normal" method, in which each item occupies an entire line of the display, and the "Compress" method, in which each of four items is squeezed into half of the display. As with logging, the third and fourth items are selected by the contents of the slot after the one selected for normal display.
Squeezing items into nine characters (to allow some separation between the two that share a line) results in very terse to non-existent descriptions. With some items there is also loss of precision, although this should be of little practical consequence. The display is hard to read, especially at a glance. Therefore, I strongly recommend using this display method with caution to avoid distraction while driving. Set up only items that you will be able to quickly recognize. (You will need to perform setup with the normal display method.) Note the appearance of the display when the car is stationary to help you get the information you're looking for quickly without looking down from the road for more than a fraction of a second.
The selected choice for this option is saved at power-down and will be effective at the next power-up.
This option sets the rate at which the Mini-Scanner sends requests for data items to the vehicle. Choices for the option are Slow, Normal and Fast. The default is Normal. The selected choice for this option is saved at power-down and will be effective at the next power-up.
The request rate is controlled in the Mini-Scanner by changing two parameters of the communication protocol. The "inter-byte" time (P4) is the time that the Mini-Scanner waits after completing the transmission of one octet of a request message before it begins the transmission of the next. ISO9141 requires this time to be in the range 5 to 20 ms. The "inter-message" time (P3) is the time that the Mini-Scanner waits after receiving the last octet of a response message from the vehicle before it begins the transmission of the first octet of the next request message. ISO9141 requires this time to be in the range 55 to 5000 ms. The values of these parameters for the three request rates are shown in the following table:
|
Rate |
Slow |
Normal |
Fast |
|---|---|---|---|
|
P4 (inter-byte time) |
15 ms |
10 ms |
5 ms |
|
P3 (inter-message time) |
1000 ms |
350 ms |
55 ms |
The Prius seems to be perfectly happy with the Fast request rate all the time. So, the slower rates might end up not being very useful, except to limit the length of log files taken over a long period of time. I will probably scrunch the three choices up closer together at some time by decreasing P3 to 500 ms and 160 ms for Slow and Normal, respectively.
This option sets the state of the display backlight. Choices for the option are Off and On. The selected choice for this option is not saved at power-down. At power-up, the backlight is Off unless the Left button is held down while the On/Reset button is released, in which case it is On.
This option controls whether or not you can clear Diagnostic Trouble Codes (DTCs) when in Trouble Codes mode. The default is disabled. You need to change it to enabled if you want to clear DTCs. The selected choice for this option is saved at power-down and will be effective at the next power-up. However, you should be very sure about what you're doing when you clear DTCs and keeping this option disabled is a good idea.
This option sets the number of times that the Mini-Scanner will retry a message to the vehicle after getting no response. Choices for the option are 0 to 5 in increments of 1. The default is 2.
The selected choice for this option is saved at power-down and will be effective at the next power-up.
This option sets the length of time that the Mini-Scanner pauses after having decided to turn itself off before it actually powers off. This pause gives the user a chance to see what is happening and read displayed messages. Choices for the option are 2 to 7 seconds in 1 second increments. The default is 5 seconds. The selected choice for this option is saved at power-down and will be effective at the next power-up. If the Mini-Scanner needs to save new settings (favorites or option choices), the power-down delay will be increased by 50% to accommodate the additional message on the display.
Last edited December 4, 2003. All material Copyright © 2003 Graham Davies. No liability accepted.