Use this forum to chat about hardware specific topics for the ESP8266 (peripherals, memory, clocks, JTAG, programming)
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By AJITnayak
#78179 Dear all,
This is my first thread in this forum. I am using Nodmecu unit from amica and Arduino 1.8.5.
I am trying to interface nodemcu with Modbus RTU device. When i connect Tx and rx line The device works normally.There is no issue in communication

Problem i am facing while communicating while restart of nodemcu or power off to power on.During this situation device wont come online itself. If i remove the tx and rx line if it restart/ Reset device start communicating . it start receive response when device tx and rx line connected. during this stage i wont get any problem in communication.

How can i overcome this issue. as product i wanna sale.It wont work at all unlsess tx and rx line are isolated. Some application where tx and rx lines used as digitalo it wont lead any problems.
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By QuickFix
#78209 You are aware that the RX and TX pins on the NodeMCU are also directly connected to the on board RS232 - USB convertor?