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Welcome to the official site of the Virginia Department of Motor Vehicles, with quick access to driver and vehicle online transactions and information. Need to Pass the Doubles and Triples Test? Get your endorsement with ease, we have prepared 5 CDL Doubles and Triples Practice Tests to help you study for FREE.
In this topic, we discuss class-based extensions to the Kernel Mode Driver Framework (KMDF). Before you read this topic, you should understand the ideas presented in Minidrivers and driver pairs and KMDF as a Generic Driver Pair Model.
For some device classes, Microsoft provides KMDF extensions that further reduce the amount of processing that must be performed by KMDF drivers. A driver that uses a class-based KMDF extension has these three pieces, which we call a driver triple.
- The Framework, which handles tasks common to most all drivers
- The class-based framework extension, which handles tasks that are specific to a particular class of devices
- The KMDF driver, which handles tasks that are specific to a particular device.
The three drivers in a driver triple (KMDF driver, device-class KMDF extension, Framework) combine to form a single WDM driver.
An example of a device-class KMDF extension is SpbCx.sys, which is the KMDF extension for the Simple Peripheral Bus (SPB) device class. The SPB class includes synchronous serial buses such as I2C and SPI. A driver triple for an I2C bus controller would look like this:
- The Framework handles general tasks that are common to most all drivers.
- SpbCx.sys handles tasks that are specific to the SPB bus class. These are tasks that are common to all SPB busses.
- The KMDF driver handles tasks that are specific to an I2C bus. Let's call this driver MyI2CBusDriver.sys.
The three drivers in the driver triple (MyI2CBusDriver.sys, SpbCx.sys, Wdf01000.sys) combine to form a single WDM driver that serves as the function driver for the I2C bus controller. Wdf01000.sys (the Framework) owns the dispatch table for this driver, so when someone sends an IRP to the driver triple, it goes to the wdf01000.sys. If the wdf01000.sys can handle the IRP by itself, SpbCx.sys and MyI2CBusDriver.sys are not involved. If wdf01000.sys cannot handle the IRP by itself, it gets help by calling an event handler in SbpCx.sys.
Here are some examples of event handlers that might be implemented by MyI2CBusDriver.sys:
- EvtSpbControllerLock
- EvtSpbIoRead
- EvtSpbIoSequence
Here are some examples of event handlers that are implemented by SpbCx.sys
- EvtIoRead
. In either case, additional testing and fees will be required. CDL Endorsements
After you have satisfied the requirements for a Class A, B, or C commercial driver's license, you may also need to pass additional written and road driving tests to operate special types of commercial motor vehicles.
Below is a list of the federal endorsement codes you may need in addition to your CDL and what tests will be required by your state.
Driver Trip Sheet Format
- H Endorsement: Required for vehicles containing hazardous materials.
- Requires a written knowledge test.
- N Endorsement: Permits you to operate tank vehicles.
- Requires an additional written knowledge test.
- P Endorsement: Allows you to operate a vehicle that carries over a specified number of passengers (the exact number may depend on your state).
- Requires written knowledgeANDroad skills tests.
- S Endorsement: Permits theoperation of a school bus.
- Requires written knowledge AND road skills tests.
- ALSO requires separate application forms, fees, and background checks. See our guide to passenger and school bus endorsements.
- T Endorsement: Allows you to tow a double or triple trailer.
- Requires an additional knowledge test.
- X Endorsement: Combination endorsement for HAZMAT and tank vehicles.
- Requires a written knowledge test.
Check with your state to determine the exact process required for adding an endorsement to your commercial driver license.
CDL Restrictions
A restriction placed on your commercial driver's license may keep you from operating certain types of vehicles.
Common federal CDL restriction codes are listed below:
- E Restriction: Prohibits you from operating vehicles with a manual transmission.
- Occurs when you take your skills test in a CMV with automatic transmission.
- L Restriction: Prohibitsoperation of a vehicle containing a full air brake system.
- Occurs if you:
- Fail the Air Brakes Knowledge Test.
- Incorrectly identify air brake system components.
- Fail to properly conduct an air brakes system check.
- Take the road skill test in a CMV lacking a full air brake system.
- Occurs if you:
- Z Restriction: Also prohibits you from driving a CMV with full air brakes.
- Occurs if you tested in a vehicle with an air over hydraulic brake system.
- M Restriction: Restricts you to operating a Class B or C passenger vehicle/school bus ONLY.
- Occurs if you possess a Class A CDL, but earned your passenger/school bus endorsement driving a Class B vehicle.
- N Restriction: Restricts you to operating a Class C passenger vehicle/school bus ONLY.
- Occurs when you possess a Class B CDL, but earned your passenger/school bus endorsement driving a Class C vehicle.
- Restriction: Prohibits you from driving any Class A vehicle that has a fifth wheel connection.
- Occurs when you take your skills test in a CMV that has a non-fifth wheel connection, such as a pintle hook.
- V Restriction: Indicates that a medical variance has been reported by the Federal Motor Carrier Safety Administration (FMCSA).
- This may occur, for instance, if you have a vision or diabetic waiver issued by the FMCSA.
Depending on your state, there may be additional restriction codes that can be placed on your CDL license.
1more Triple Drivers Specs
Removing a CDL Restriction
If you wish to remove a restriction from your CDL, you may be required to complete or provide:
Drivers Triple Six
- Additional written knowledge tests.
- Additional road skills tests.
- This includes testing in a vehicle meeting the requirements indicated by the restriction.
- Further medical evaluations.
- Payment of additional fees.