![]() When USB COM port disconnected error occures, handler OnAfterClose is executed and exception "Port Disconnected" (TComException = CE_PortDisconnected) is generated. Solution isn't perfect and still is possible to suspend application on infinite WaitForSingleObject, especially in the case of very slow transmission speeds (300-600 bauds), but it's a lot better than before. The most common version of IEEE 1394 is known as IEEE 1394a, and is also known as FireWire 400.ComPort library with USB COM port disconnected issue fixed. ![]() IEEE 1394 (FireWire) IEEE 1394 is a family of high-speed bidirectional serial transmission ports that can connect PCs to each other, digital devices to PCs, or digital devices to each other. However, mixing slower and faster devices can cause the faster devices to slow down unless you use a host adapter with dual buses that can run at different speeds. SCSI host adapters are generally backward compatible, enabling older and newer SCSI standards to be mixed on the same host adapter. Popular SCSI Standards Popular Name Speed Number of Devices Data Bus Signal Type Fast 10MBps 7 8-bit SE Fast-Wide 10MBps 15 16-bit SE Ultra 20MBps 7 8-bit SE Ultra-Wide 20MBps 15 16-bit SE Ultra2 40MBps 7 8-bit LVD Ultra2Wide 80MBps 15 16-bit LVD Ultra 160 160MBps 15 16-bit LVD Ultra 320 320MBps 15 16-bit LVD 8-bit versions of SCSI use a 50-pin cable or a 25-pin cable wide (16-bit) versions use a 68-pin cable. ![]() The major SCSI standards are listed in Table 3-3. SCSI Standards SCSI actually is the family name for a wide range of standards, which differ from each other in the speed of devices, number of devices, and other technical details. The parallel (LPT) port is unusual because it uses two completely different connector types. If you use more than one device, you could have problems getting the devices (not to mention the printer) to work reliably. Although it's theoretically possible to create a long daisy-chain of devices ending with a printer, in practice you should have no more than one device plus a printer plugged into a parallel port. CAUTION Devices other than printers that plug into the parallel (LPT) port have two connectors: one for the cable that runs from the device to the parallel port, and another for the cable that runs from the device to the printer. ![]() Although newer devices in these categories are now designed to use USB or IEEE 1394 ports, the parallel port continues to be an important external I/O device for older systems. Historically, the parallel port has been among the most versatile of I/O ports in the system because it was also used by a variety of devices, including tape backups, external CD-ROM and optical drives, scanners, and removable-media drives such as Zip drives. ![]()
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