Within your driver source file, you will need to create the following modules. These modules are well-defined entry points that are called by VTSDriver in VTSDrvr.web.
VTSRead - reads VTS variables from an input device.
VTSWrite - writes VTS variables to an output device.
VTSGetAddr - gets the VTS addresses and parses them.
You must also define the following variables:
Driver This is used internally by the VTS engine and should not be set by the driver tag code being created. It will automatically be linked to the instance of VTSDriver that will be created for this driver instance.
Ready This variable should be set to 1 by the driver tag code when it is safe to start reading or writing I/O.
Value This typically defines the error state of the driver. The VTS engine is responsible for setting this value. It should not be set by the driver tag code being developed. Typically, its value will be an error code, where 0 indicates no error.