In certain cases we need to use more than one Serial port in the case of arduino, I use the arduino mega 2560 which has 4 serial ports including the programming port, in the case of arduino's as the nano has a single programming port and as a solution Have created the softwareserial library, given the incompatibility of certain functions the softwareserial library for arduino does not work on esp8266.

Softwareserial Library

I have tested with ESP8266 NodeMCU and SoftwareSerial library of the espsoftwareserial repository created or supplied by plerup thanks for your contribution to the community.

Complete tutorials available
Tutorial completo: PDAControl Español: ESP8266 2 puerto seriales con libreria SoftwareSerial

Full Tutorial: PDAControl English ESP8266 two serial ports with SoftwareSerial library

Step 1: ESP8266 12E NodeMCU & SoftwareSerial

ESP8266 12E NodeMCU & SoftwareSerial

Test
To verify the operation of the softwareserial library, I downloaded the library for esp and I have temporarily replaced the serial software version for arduino.

Conclusions
Although this is a basic test, it requires more complete tests regarding the configuration of more serial serial ports. The idea is to use this library in future integrations in Modbus RTU, Recommended TrialCommand.com.