FTDI Community

General Category => Discussion - Hardware => Topic started by: ivanooi on December 12, 2020, 03:09:04 AM

Title: Questions on ft4232h to rs485
Post by: ivanooi on December 12, 2020, 03:09:04 AM

Hi all ,

I am using ft4232 as converter to rs485 and I have some questions :

1) can I configure the txden = ri enable without the need for an eeprom ?
2) I have the usb to rs485 plus four evaluation module and wondering do you have the schematic for that board?
3) why for rs485 module local echo is enabled?

Thanks

Title: Re: Questions on ft4232h to rs485
Post by: FTDI Community on December 15, 2020, 04:40:56 PM

Hello,

In order to configure TXDEN, an external EEPROM is required:

* RI#/ or TXDEN is selectable in the EEPROM. Default is RI#.

I can provide the USB-COM485-PLUS4 if you contact us via email:

https://www.ftdichip.com/FTContact.htm (https://www.ftdichip.com/FTContact.htm)

RS485 systems often have local echo enabled. This means any data transmitted by a device is echoed back to itself.

There is a hardware option to disable local echo on the USB-COM485-PLUS4. Please refer to the USB-COM485-PLUS4 Datasheet (https://www.ftdichip.com/Support/Documents/DataSheets/Modules/DS_USB-COM485-PLUS4.pdf).
Connect pin7 and pin 8 can disable the local echo function. The local echo is enabled by default.

Best Regards,
FTDI Community