>Hi Ed, So before buying a receipt or barcode printer, I should ask if it comes with an ActiveX control? Is it difficult to impliment? Where can I read more about using ActiveX controls? Thanks.
You can try the VFP On-Line Help file, Chapter 16, entitled "Adding OLE", goes into this in detail. Using ActiveX controls is simple; it's much the same as using VFP native objects or any other COM component. When purchasing the printer, I'd find out up front exactly how it was controlled, since typically, these printers don't follow the typical Windows GDI printer model of spooling, resetting the printer to a known state at top of page, and often require that you send specific control sequences to directly control printer functions, rather than offering hardware-independent mapping of Windows fonts and paper charracteristics like a Windows GDI-interfaced printer typically offers. In many cases, a receipt printer is combined with a register or cash drawer unit, and sending a specific control sequence to the device may open the cash drawer. Since the behavior you want isn't what the Windows GDI usually offers, it's best to find outup front how to interface and control the device as you want it to work.
At least that's my experience here - my main experience related to this comes from handling barcode printers, postage meters, pre-printed multipart form handling and the like; it appears isomorphic, but other people who do POS may suggest other methods. AFA barcode and stripe readers, I think my experience using both applies; wedge devices are easy to handle, since they're handled in the same fashion as keyed text; I've worked with Smart Cards as well, and there, use of an ActiveX control in VFP, or an API library interface, is generally required, since these devices don't map identically in function to other standard Windows UI interfaces.
As far as interfacing lots of devices, I'll stand by my recommendation of USB interfaces; USB offers an easily-expanded interface that can handle multiple devices with a single interrupt; adding and configuring multiple serial ports is much more complex, and even where a device doesn't offer a USB interface, there are several companies that offer serial and parallel port to USB adapter hardware that lets RS-232 and EPP/ECP parallel devices to use the USB adapter.
