I have an old piece of instrument that suppose to connect with a Windows XP machine. I keep getting "Framing Error" messages on the instrument panel while the PC side shows that the instrument could not be found.
The instrument uses RS232C in a 9 pin serial port to connect to the PC. If I understand correctly, RS232C is the same as the prevailing RS232 on Windows XP. I have tested the serial port on the XP machine with Hyper Terminal, and made sure I use the proper "straight through" type of cable. The cable has been used on the same location with other instrument and worked properly.
In order to connect the instrument with an XP machine, I have set the following parameters to be the same on both sides:
Baud rate 9600 Data Bits 8 Parity None Stop Bits 1 Handshake None
However, on the instrument side, there is an item called "terminator" with CR, LF, and CR+LF settings, which is not available on the serial port settings for Windows XP. I tries all three settings but none worked.
What should I do next?
According to the service manual:
An RS232C format serial port is available at the DE-9 connector J3. U8 provides voltage level translation from +5 volts and ground to ± 12 volts. Direct I/O control lines are used for all signals because of the timing critical nature of the communications protocol. Two data lines (TXD/RXD) are used and two control lines (RTS/CTS) are available for hardware handshaking if enabled by the software. ....
What are "direct I/O control lines"?