#RTS polarity in RS485 mode

Embedded Devices NET+OS
1

Dear Support,

In RS485 mode it seems to me that the #RTS line goes low when data is to be sent. It is possible to make this signal with a different polarity without hardware changes?

We are using RS485 in 2-wire mode and I would like to directly interface the module with our RS485 driver. Of course an inverter is an option but if we can do it by software I would prefer it.

Thanks,
Christian

2

Hi,

Bit of a late reply but this is the code I used when I needed to set up the FIM UART on com/5. Had to have a normal Tx operation and an inverted RX for the hardware I was talking to:

#define GPIO_FUNC_0 0x0000
#define GPIO_FUNC_1 0x0008
#define GPIO_FUNC_2 0x0010
#define GPIO_FUNC_3 0x0018
#define GPIO_FUNC_4 0x0020
#define GPIO_D_OUT 0x0004
#define GPIO_INV 0x0002
#define GPIO_PUDIS 0x0001

/*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
EnablePort5

Description:
Helper routine to switch the GPIO multiplexer to allow Port5 (FIM1) to
operate.
Parameters
none

Return
Status

static int EnablePort5(void)
{
  int state;
  state = NAconfigureGPIOpin(72, GPIO_FUNC_1 | GPIO_INV, 0x01);
  state |= NAconfigureGPIOpin(73, GPIO_FUNC_1, 0x01);

  return (state);
}


Regards
   Roy