rs485 device through rs232 port?

[jccorreu1]

BTW thanks for your help, you're doing a little more than I was expecting anyone to do.

Yes I have dbl checked the settings in the controller and the vi (parity, baud, protocol, stop bits, address).  ANd I've tried the reverse wiring, but I may not have tried all the possible combinations (flowcontrol on or off, manual setting RTS/CTS, etc..) that I'm uncertain of....  I'll go back and try the entire set of combinations that I have before me.

which brings me to a little more of a question about how the flow control works with Labview.
When I select FLOWCONTROL=RTS/CTS you said that I do not use property nodes to manually set those lines (which I verified when receiving the errors).  So which should I use, doing it manually in between writes and reads, or setting the FLOWCONTROL?

How does the FLOWCONTROL operate?  I've not been able to find any real documentation about NI's implementation.  I take it that its the same as if I had set the flow control in MAX, or in XP's system hardware device manager?

As far as general documentation goes I've just found the general statement of what FLOWCONTROL is, not really how it works.  Same with NI"s serial/VISA implementation.  Does anyone know some really good documentation on these subjects that gets a bit more complete treatment (without taking me all the way to the machine code)?

I really do want to understand more of what's going on.  I am then in a better situation to track down problems, and may be able to help someone else in the future.

James

[Wayne.C]

James,

I suggested reversing the TX and RX on the RS485 because not all instrument manufacturers label the two wires the same.  Because the loopback test worked, (R-ON, T-ON mode ) I do not believe that the problem is between the pc and the adapter.  I believe that the problem is either a cabling issue between the adapter and the FUJI device or the formatting of the command you are sending.

When you set FLOW CONTROL=RTS/CTS in your vi, you are changing the settings for the COM port driver that is installed to interface the OS to the actual COM port hardware.  You are correct in that it is just like using device Manager in windows to change your COM port settings.  The actual control/manipulation of the RTS/CTS lines is then handled automatically by the COM port.  This is my prefered way to do this because it is often faster and much simpler that using the property nodes.

For the nitty gritty on RS232 I suggest you look up the RS232 standard.  It should cover the varous handshaking schemes.

[jccorreu1]

To let you know I did get it working.  It was to do with the converter.  I got a different converter, that is designed to go to a 2-wire rs485 device and it worked as soon as I plugged it up.

I have read a bit of the rs232 standard, actaully the way I learned in school to interface with the serial port was using the portin.vi and portout.vi.  There are many details I've had to re-read and will have to look up again if ever I need.

I guess what I meant was how Labview flowcontrol does the timing.  But from what you've said and what I've read it probably works by immediately setting the RTS whenever it is not transmitting. (kind of like how my new converter handles it)

thank you both for your time and effort
James