modbus rs232 pin configuration in labview

[alcesco]

Hello,

I am working in a Modbus application and I have a few questions about it, I am using NI_MODBUS 8.2 library.

I have 2 computer, in one of them I programed a master, in other I have a slave with a Modbus emulator program (Modsim32, trial version), I would like to know the pin configuration using by labview for the serial port , I am using usb to rs232 adapter for both computers  but I could'n establish any connection.

The purpose of the aplication is to connect the labview Modbus master to 10 slaves, but the slaves will use rs485 serial protocol. Is it possible to change rs232 to rs485 by software in labview (without additional hardware)?

Thanks in advance

Antti.

[mik174]

"The purpose of the aplication is to connect the labview Modbus master to 10 slaves, but the slaves will use rs485 serial protocol

"Is it possible to change rs232 to rs485 by software in labview (without additional hardware)?"
No, by just software methods you can't do this.

RS485 and RS232 (Com-port at PC) have different physically realizations.

One more moment: RS485 has two connection scheme: 2-wire and 4-wire.

Look for example at http://www-micrel.deis.unibo.it/~augusto/comm485.pdf for more information

there are many converters RS485 to RS232, but look attantively for connection 2 or 4, it's very important

[alcesco]

Thank so much.