RS485

[Ronald]

Hi,

As I'm using more than one brand of frequency converter, I'd like to
'standardize' communication with them by using RS485 in combination with
LabView. I've bought a RS232-RS485 converter and with the provided software
I can control my converters. Is there any way that I can 'listen' at my
serial port (RS232) to find out how the communication is done for each
Frequency converter?

Thanks,

Ron@ld

[Al_S]

You can monitor your RS-232 port with another RS-232 port. You can't do it just in software and you can't do it with only one RS-232 port: if two programs are trying to read one port, only one will get the data. If you have another RS-232 port available, make a monitoring cable:
1. Wire all pins of a DB9 male connector to a DB9 female, pin 1 to pin 1, etc.
2. To a second DB9 female, connect pin 2 to pin 2 of the first DB9.
3. Connect pin 3 of the first DB9 to the anode of a diode (like 1N4148).
4. Connect the cathode of the diode to pin 2 of the second DB9 female.

You can use Hyperterm (or Labview) to monitor the second RS-232 port.

[Al_S]

A couple other details:
Wire pin 5 of the second DB9 female to pin 5 of the first.

Connect the first DB9 female (with 9 wires) to the PC RS-232 port used for your converter.
Connect the converter cable to the DB9 male.
Connect the second DB9 female (with three wires: two on pin 2 and one on pin 5) to your PC's second RS-232
port (or an RS-232 port of another PC).

You'll need to know (or figure out by trial and error) the baud rate used by the converter and setup Hyperterm to the same baud rate.

[Ronald]

Thanks for this!

I guess it is also possible to use another computer with an RS232 to monitor
the activity of the other computer??

Ron@ld
Al S schreef in berichtnieuws
50650000000500000011B70000-1031838699000@exchange.ni.com...
> A couple other details:
> Wire pin 5 of the second DB9 female to pin 5 of the first.
>
> Connect the first DB9 female (with 9 wires) to the PC RS-232 port used
> for your converter.
> Connect the converter cable to the DB9 male.
> Connect the second DB9 female (with three wires: two on pin 2 and one
> on pin 5) to your PC's second RS-232
> port (or an RS-232 port of another PC).
>
> You'll need to know (or figure out by trial and error) the baud rate
> used by the converter and setup Hyperterm to the same bau
d rate.

[Al_S]

Yes, you can use another PC or even an old serial terminal (like a DEC VT100 or VTxxx, if your baud rate is slow enough).

If the second PC or terminal has a 25 pin RS-232 port, you need to change the pins on what was the second DB9 female connector: pin 2 of the DB9 goes to pin 3 of the DB25; pin 5 of the DB9 goes to pin 7 of the DB25. Leave the pins on the other two DB9 connectors alone (wired 1 to 1).