[From QnA] WIZ108SR RS485

S2E Module WIZ107/108SR
1

I am using WIZ108 as RS485 Interface. Communication is working well. I can also receive messages.
I cannot send any message. The 485_SEL Pin is not connected, but message is not transmittet via RS485 Pins TRXD+ and TRXD-. Message is only transmitted on TXD+ and TXD-. It seems, that Pin 485_Sel is not switched by the system. Is there a special setup needed?

2

Dear customer,

Please confirm the 485sel pin level when you send the data.
When you send the data, 485sel is switching.(high->low)
Thanks,
WIZnet

3

485_SEL Pin is not connected and always Low. When I manually connect to +3.3 and transmit Data, the Data is send out on TXD+/TXD-.

4

Dear customer,

Please check the pin 2 of U2:SP3485EN.
Please confirm the pin2 level when you send the data.
When you send the data, pin2 is switching.(high->low)
thanks,
WIZnet

5

Pin2 is always low.
For my understanding: Pin2 should switch to high during sending of data and then be low again.