Read error using RS232

[qinchao]

I don't know more about the Basic programm, I download it from the radioshack website

[RavensFan]

Have you tried running that Basic code to see if it works?  (Though I'm not sure if newer versions of Windows still supply Basica or Qbasic).

Are you sure you have the right cable?  Null modem vs. straight through.

Have you tried communicating in Hyperterminal yet like Dennis mentioned?

[smercurio_fc]

I managed to dig up this page that discusses those OPEN options. It appears that the configuration is to basically ignore the state of the various serial port lines.

[AnalogKid2DigitalMan]

RTS and DTR? must not be asserted or the meter will not send data. Some details here on pg6:

http://www.utsc.utoronto.ca/~quick/PSCB01H3S/Manual/ApA.pdf

and on pg11 here:

http://www.utsc.utoronto.ca/~quick/PSCB01H3S/Manual/Ch05.pdf

As already suggested, verify your cabling and start with Hyperterminal.

-AK2DM

[qinchao]

The Basic programm is working

I have checked the serial port with Hyperterminal, I type "D", but there is nothing feed back on the screen.

[RavensFan · Accepted solution]

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AnalogKid2DigitalMan wrote:

RTS and DTR? must not be asserted or the meter will not send data. Some details here on pg6:

http://www.utsc.utoronto.ca/~quick/PSCB01H3S/Manual/ApA.pdf

and on pg11 here:

http://www.utsc.utoronto.ca/~quick/PSCB01H3S/Manual/Ch05.pdf

As already suggested, verify your cabling and start with Hyperterminal.

-AK2DM

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I found the first item on page 8 of the ApA.pdf.  That seems backwards to me for a normal serial protocol that the lines should be unasserted. 

But that explains why it won't work in Hyperterminal.  When you open the port in hypertermina DTR and RTS go high.  I don't know if there is any way to force them to be low from within Hypterminal.

Within LabVIEW, those lines can be set to low.

(Also double check your baud rates.)

Message Edited by Ravens Fan on 10-29-2008 04:14 PM

[AnalogKid2DigitalMan]

RavensFan:

I agree, probably the best best would be to leave them unwired (physically in the real world, not virtually in LabVIEW), just use the RXD, TXD, and GND wires since there is no flow control protocol.

Sorry I did not preview your attachment.

-AK2DM

[qinchao]

The problem has been solved. Thank everyone

AnalogKid2DigitalMan gave me two useful PDF.

The problem is "The instrument does not support handshaking, but the RTS line must be unasserted or else the DMM will not send.6"

When I add a property Node and set RTS state = 0 ,then it is working.

[sabrinabangert]

Hi,

I have the same problem. What can I do? Here is my error-screen:

[sabrinabangert]

Where do I have to add the property node? Here: