Solution:

Common problems and possible solutions are listed below: HARDWARE: A. Wrong cable wiring: Check if wrong cable wiring. Refer to Appendix B.3 of PCL-844H manual for precise pinouts of the connector type you are using. B. Defective control box: Cable or external module is defective. Please change another one to test again. C. IRQ conflict: IRQ is used or reserved by PCI bus. Please adjust it or go to BIOS to modify "PNP and PCI setup" configuration. SOFTWARE: A. RTS/CTS signal: PCL-844 series will check line status ( CTS ) before it sends data out if RTS/CTS flow control feature is set to ON in configuration or application program. Please see Appendix B.3 of PCL-844H manual Type 3 for proper wiring. Check the line status of the suspected port using the disgnostic LED indicators on the mini-tester. B. Existed good examples for testing: Perhaps the application controlling the board is not correctly written according to the corresponding API of the operation system. To verify, please run existing and known good application or Advantech-provided utility. For example, under Windows 95, "Hyperterminal" is good for testing COM ports. Under UNIX, "stty", "cat", or "getty" is existed program for testing tty port. C. IRQ setting: IRQ settings of software and hardware do not match.