Second RS232 port on the PC won't work.

[R]

Al S, Please see my response below, Richard.

[R]

Mike, Please see my response below, Richard."

[Al_S]

In Lots_of_serial_outputs.vi, your write loop doesn't wait for the initialization loop. To force write to wait, create data dependency by wiring any output from the initialization loop to the frame of the write loop. You don't need to do anything in the write loop with that output: just wiring it to the frame will force the write loop to wait. Search the LabView help for data dependency for more details.
But that doesn't look like the sole cause of your problem.
You duplicated the problem with Hyperterm, so it's not just a LabView problem.
Sorry: it looks like you have a hardware problem.
You have at least three options:
1. Try another PC.
2. Buy a serial card and install it in the PC. There are a lot of cards for $200 or less. Here are a couple.
htt
p://sine.ni.com/apps/we/nioc.vp?cid=1348〈=US
http://www.quatech.com/shopquatech/products/prod339.asp
http://www.bb-elec.com/product.asp?sku=232PCI2A&dept_id=40
3. Troubleshoot the hardware of your existing PC. Locate the UART chip (probably either a 16550 or a custom chip). Here's the datasheet for the 16550.
http://www.national.com/ds/PC/PC16550D.pdf
If it's a custom chip, you'll need the pinout or the motherboard schematic. Then check for continuity between the chip and the 9 pin connector. E.g., for the 16550, check between SOUT and Transmit Data (pin 3), SIN and Receive Data (pin2), and VSS and Signal Ground (pin 5).

[Remington]

Hi Richard,

Generally, the serial ports are wired the same in a PC. It is the instrument that you wish to communicate with that determines whether or not to use a null modem cable. For example, I have a digital multimeter that uses a straight-thru cable, but I also have a temperature controller that uses a null modem cable.

Have you tried communicating with your second instrument on Port 0? If so, and you are successful, then you can rule out the problem being attributed to the type of cable you are using.

By your diagnostics, your PC seems normal. Short of getting another computer, I would suggest that you install a third RS-232 card. It may be that COM2 is defective and Windows is not reporting it for whatever reason.

Remington.

[storeyk]

When i said "Right click on My computer>Properties>Hardware>Device manager>Ports", i meant "Right click on My computer>Properties>Select Hardware TAB>Click on Device manager BUTTON>Expand Ports", then you should see both the comm ports - double clicking on these will tell you their status. You should be able to view these even if you are only in the USERS group, although having administrator access at times like this is useful.

If one of the ports is not working properly or there is a device conflict you may have to change the Resource settings, but you will need Admin access to do this.

After you have solved any conflicts, if you still have problems then try pluging an RS232 Comm mouse into each port separately (you may have to reboot both times)
. The mouse should work in either port. You could also try this in safe mode (press F8 at start of reboot) on the off-chance that your 2nd port may be locked up by another application. If the mouse still doesnt work then it looks like you have a hardware problem and you should follow Al S's advice.

I hope this helps you..

Kim

[Arno Euteneuer]

Dear Richard,

Maybe this information is useful for you (or for anybody else):
Several times I had problems with the on-board serial interfaces in some of
the PCs I used. Everything worked fine with short cables, but with longer
cables (4-5m) I was not able to control my external devices at all. With an
80 ? PCI-card, having two RS232 and one parallel interface, I was able to
solve my problem.

Regards

Arno