Python: cannot receive all the data from Socket

Question

I am using the code below trying to receive all the data from I socket. When I send the SCPI command "FETCh?\\n" to the device, it returns a large amount of data, and the recv() function only returns part of it.

Does anyone know how to solve this problem? Thanks in advance!

class SCPI:
        PORT = 5025

        def __init__(self, host, port=PORT):
            self.host = host
            self.s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
            self.s.connect((host, port))
            self.f = self.s.makefile("rb")

        def scan(self): 
            self.s.send("FETCh?\n")
            data = self.s.recv(268435456)
            print(data)
            return data

Answer 1

recv returns up to the amount requested. You have to check the return value and call it again until you receive the amount expected. Implement a buffer that accumulates data and returns the exact amount requested.