USB-to-RS485 converter problem

[eepty]

I have developed a system in which each device can communicate with each other through RS485. In the protocol, if a device want to send out a packet, it will detect the RS485 bus first to check if any data still on the bus to avoid collision. The system work perfectly within its own network. It also works when I use a RS232-to-RS485 converter to connect a computer to this system. However, if I use a USB-to-RS485 converter, I found that the data crashed.

What could be the reason?

Thanks!

 

[ftsolutions]

Quite often, the RS232 <-> RS485 converters use either the CTS/RTS and/or the DSR/DTR RS232 handshaking signals to control the transmit/receive functions of the RS485 transceiver chip(s). It is possible that the USB-RS485 converter is either not using these signals, or not using them properly -- possibly because of an issue with the driver or driver configuration settings for the port.

Are you using the USB converter in the same way as the RS232-RS485 converter (for example, using Hyperterminal or PuTTY or other terminal emulator program with both devices)? Do both devices appear as Virtual COM Ports (VCP) within Windows ? Are you using Windows, or some form of Linux, or Mac OS on your computer?

 

[udhay_cit]

What is the chip you are using for USB to Serial conversion. If it is FT232 then it has CTS & RTS signals. I'm using lot of the chips with out any issue. If you need schematic of the converter then i can provide...