Can I get POS cash register print data to a Raspberry Pi device? Need the print preview on the raspberry pi display according to the POS print signals.
I don't think there is enough information here to be able to answer your question. Especially details on what the output from the POS looks like. Is it a PDF? I'm sure you can "send" a PDF to a raspberry pi and display it on the monitor.
Acculally i want to remove my existing thermal printer & connect RPi 3 on there. It's must when you send the print signal the rpi shoul received as a printer & show the bill on that display.
I believe you could use a virtual printer. If you can then adjust your POS to print to that virtual printer, I think it could work. The POS and raspberry pi would not need to be physically connected, they would just need to be on the same network. You could write software on the raspberry pi to display that print job on the screen.
If you are hoping to physically plug in your raspberry pi to your POS and have your POS think the raspberry pi is the printer - I am doubtful this could be made to work. That is assuming your printer is a USB printer. You have not given us much detail so it's hard to help you. If your thermal printer is a serial device - then I think the raspberry pi is capable of receiving that data and displaying it.