It's unmodified, other than some header comments I added attributing it to Cory. Internally, all Protocol commands are rendered into byte streams and automatically transported to the sign using Cory Smith's DBComm class. It is almost completely Private, however, you still need to provide the Sign object with a comm port number. This Private class defines the communication method between the PC and the sign. Note that a few of the Protocol Enums are exposed in the Sign methods - for transitions and so forth - as these are unavoidably determined by the underlying protocol. ''' Public Sub SetDateAndTime( ByVal dt As DateTime)ĭim dc As New (dt) ''' ''' Sets the date and time on the sign to any arbitrary date/time The Sign.SetDateAndTime method illustrates how this works: The child commands must override the FormDataField method, which returns the string of text specific to that particular command class. All commands inherit from the BaseCommand class, which implements the standard Alpha packet format. Additionally, if you want to preview a "pretty printed" version of the command, you can call the overridden ToString() method for the command. This Private class factory defines all the low-level commands necessary to talk to the sign, which can all be rendered to a byte stream via the ToBytes() method. It drives the Protocol and RS232 classes behind the scenes, so the user is protected from the complexities of both the Alpha Sign Communications Protocol and RS-232 serial communications. This is the primary Public interface for the sign. This isn't a big deal in practice, but it cannot be abstracted away, so you must be aware of it.Įarly on, I made the decision to implement the API as a set of three classes: Any attempt to allocate more memory later will destroy all the existing memory allocations! Be sure to allocate all the memory you'll need before writing anything to the sign. Any time you program the sign, you must allocate all the memory you'll need in advance. NET, because this one took me a while to wrap my head around. I guess I've been spoiled by the automatic memory management and garbage collector of.
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