Attached are two Flowcode charts that will allow 2 x ESP8266 modules to pass data into Excel (or whatever). Please just consider this a framework to illustrate how it could be done and it can easily be tailored to suit. I broke it down into Macro sections in an attempt to make it easier to read. I'm not a programmer, I am a Flowcoder....
In this example they both connect to a WiFi router and communicate via the router. It should be a simple matter to have the receive module be an AP too, to allow direct ESP to ESP connection. If I get time later I'll perhaps provide a further example. However based on my experience with ESPs, it may help extend your range between modules by connecting via a WiFi router.
The receive has a LCD display, the ESP8266 component, a Circular Buffer and a UART component. The chip is a PIC18F46K22 simply because it's the only one I had with 2 x UARTS. Using Flowcode it's a simple matter to change the target chip. The chip doesn't need to be particularly powerful but does need two UART ports, one for the ESP Module and the other to connect to your PC (or whatever) and I suppose it could be a software port but I haven't tested.
You will need to enter your own WiFi credentials (SSID, Password) and for the Send module the IP address of the Receive ESP. This can either be obtained from your router or read from the display. You could of course omit the receive LCD entirely but then you would need to get the IP from router logs or force the ESP to have a fixed IP.
In the receiver, UART Ch1 is Port C pins 6 and 7 (tx/rx) and this connects to the ESP module. Use level shifting on ESP Rx if necessary.
UART Ch2 is Port D pins 6 and 7 (tx/rx) and this connects via a TTL-USB Serial Converter to your PC (or whatever).
To test/use either connect the receiver UART output to your PC running "Terminal" or to Excel DataStreamer and have that running.
The receiver will upon booting send out a "Test OK" message on the UART and you should receive that on your PC. It will then, if successfully connected to your WiFi display it's IP address.
Upon receipt of data it will display the data on the bottom line and pass it on to your PC.
Run the Receiver first and all being well it will display (amongst other info) it's IP address. Take note of this.
Not much more to say about it really.
The Send chart only has the ESP component, but of course you can add in whatever sensors you like. I again broke the chart into Macros in an attempt to make it easier to read.
Upon booting, all being well the ESP will connect to your Wifi, then open a connection to your Receive module. (if monitoring the Rx with "Terminal" it should display "connect"). It will then Loop transmitting your data every x-seconds.
I have used Dummy Data in CSV format (12.34,56.78) but what is important is how this is obtained and processed for transmission.
Whatever data you want to send needs to be in String format (e.g. "Test" or "123.456" or suchlike). To send this we first obtain it's length and tell the ESP we are about to send a string of length "x" before sending our data.
The chart loops around this get data / send data every x-seconds and in the example it is five seconds. In testing I've had it sending every 250mS but I haven't really explored this aspect.
Hopefully this will be of help, and I'll look at having the receive ESP be an AP too, eliminating the need for a WiFi router.
Regards