# RS485 without MODBUS using UNO R4 WiFi

**URL:** <https://forum.arduino.cc/t/rs485-without-modbus-using-uno-r4-wifi/1392731>\
**Category:** General Guidance\
**Created:** [June 30, 2025, 2:19pm UTC](https://forum.arduino.cc/t/rs485-without-modbus-using-uno-r4-wifi/1392731 "2025-06-30T14:19:01Z")\
**Posts on this page:** 1\
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**Author:** ![markd833](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/markd833/32/1186928_2.png) [@markd833](https://forum.arduino.cc/u/markd833)\
**Post date:** [June 30, 2025, 3:42pm UTC](https://forum.arduino.cc/t/rs485-without-modbus-using-uno-r4-wifi/1392731/2 "2025-06-30T15:42:51Z")

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I don't own an R4 Wifi, but do you need software serial? From what I've read in a post by @UKHeliBob quoted below, it seems that if you are using pins 0 & 1 for your RS485 comms then maybe it’s not required :

> [@Serial1 Serial - differences and how to?](https://forum.arduino.cc/t/serial1-serial-differences-and-how-to/1325960/2):
>
> The one named Serial communicates with the PC using the USB cable plugged into the R4. It is used to upload code and to interact with the Serial monitor in the IDE
> 
> The other one, named Serial1, uses pins 0 and 1 of the R4 to communicate with devices, such as a GPS, attached to those pins.
> 
> To use Serial1 just refer to it by its name as you would Serial. For instance, `Serial1.begin(115200);` `Serial1.read();` etc

In addition, you can then use the flush() function to wait for the transmission to complete before switching back to receive.

As you are also using external hardware, you should provide details of how you have connected that up to you UNO R4.

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