Electronic – RS232 Unusual “Framing Error”

rs232serial

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?

Edit:

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"?

Best Answer

I found a copy of a service manual here: https://archive-resources.coleparmer.com/Manual_pdfs/genesys%2020%20service%20manual.pdf

It says:

  1. Ensure the RS232 setup on the GENESYS 20 is set up correctly by following these steps:

    a. Press the Utility key.

    b. Use the down arrow key until you see the RS232 Setup option on the display. To change any of the settings of the RS232 setup, press CHANGE, then use the up or down arrow keys until you getthe correct setting and then press ACCEPT.

    c. Set Baud Rate for 9600

    d. Set Data Bits for 8

    e. Set Parity for None

    f. Set Stop Bits for 1

    g. Set Handshake for CTS/RTS

    h. Set Terminator for CR+LF

    i. Press the ESC key to go back to the normal menu

In particular, I noticed that the recommended handshake is CTS/RTS. Probably worth trying that.

Update: I also found a copy of the operator's manual here: http://photos.labwrench.com/equipmentManuals/1726-1828.pdf

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