Check presence of a file

[Steffenwolt]

Thanks everybody and my apologies for the confusion caused by my unfamiliarity with the BB.

I got the problem solved with thanks to killirrex for putting me on the right track.


The whole scripot now looks like:

#!/usr/bin/env python

      #Versie 2.3; 21mei2018
      #Dit programma leest elke sensor apart uit en slaat aan het einde
      #de resultaten op in een csv file.
      #Importeer benodigde libraries.
      #21/05File not found opgelost.

import sys
import time
import csv
import os
import spidev
import RPi.GPIO as GPIO

spi = spidev.SpiDev()
spi.open(0,0)
GPIO.setmode(GPIO.BCM)
GPIO.setwarnings(False)
GPIO.setup(22,GPIO.IN)
GPIO.setup(27,GPIO.OUT)
GPIO.setup(23,GPIO.OUT)
GPIO.setup(24,GPIO.OUT)
GPIO.setup(25,GPIO.OUT)

def read_MCP(sensorid):         #Function reads MCP3008.
        adc = spi.xfer2([1,(8+sensorid)<<4,0],20000)
        adcread = ((adc[1]&3) << 8) + adc[2]
        return adcread

def read_ds18b20(sensorid):     #Function reads DS18B20 sensor.
        device="/sys/bus/w1/devices/"+ sensorid +"/w1_slave"
        try:
            with open (device) as tfile:
                text=tfile.read()
        except FileNotFoundError:
            GPIO.output(25,True)
            notemp = 9999
            return notemp
        sensor_data =text.split(" ")[20]    #Select 21st word start with zero.
        # Haal 't=' weg en maak floating
        temp_raw = float(sensor_data[2:])   #Remove 'T="and make floating.    
        #print (temp_raw)
        temp = temp_raw
        digitemp = '%.1f' % temp            #Round to one decimal.
        return digitemp
    
datum = (time.strftime('%d/%m/%Y'))     # Define date/time variables.
tijd = (time.strftime('%H:%M:%S'))

GPIO.output(25,False)                   #reset FileNotFound LED

while True:

    while True:

        time.sleep(1)
        if GPIO.input(22):          #Contact key is ON
            GPIO.output(27,True)    #Turn on LED indicator.
            break
        else:                       #Contact key is dus OFF
            GPIO.output(27,False)   #LED indicator OFF
            print ('Schakelaar is UIT')

# Checked water level BB with key OFF
                #Check watersensor SB, channel0 of ADC.    
            level = read_MCP(0)
            level_SB = round(level,1)
            print (level_SB)
            
# Turn on the SB pump if value > 510.
            if (level_SB) > 510:
                GPIO.output(23,GPIO.HIGH)    #LED/pomprelais SB ON.
            else:
                GPIO.output(23,GPIO.LOW)     #LED/pomprelais SB OFF.

               #Check watersensor BB, channel1 of ADC.
            level =read_MCP(1)
            level_BB= round(level,1)
            print (level_BB)
            
# Turn on the BB pump if value > 510
            if (level) > 510:
                GPIO.output(24,GPIO.HIGH)    #LED/pomprelais BB ON.
            else:
                GPIO.output(24,GPIO.LOW)     #LED/pomprelais BB OFF.            

# Exec DS18B20 function for sensorID's below.
    temp1 = float(read_ds18b20('28-000009aeba12'))      #Motor 1
    temp2 = float(read_ds18b20('28-000009aeba12'))      #Motor 2
    temp3 = float(read_ds18b20('28-000009adc801'))      #Buitentemperatuur

# Define 'lijst'.   
    lijst = [0,0,0,0,0,0,0,0]

# Exec function 'read_temp36' for each ADC channel.
    for offset in range(0,8):
        adcread = read_MCP(offset)
        print (adcread)
        result = (adcread*330)/float(1024)
        lijst[offset] = adcread
        offset +=1              #Decrease offset by 1
       
    data = [datum,tijd,temp1,temp2,temp3,round(lijst[0],1),round(lijst[1],1),round((((lijst[2]*3.3/1024)-0.52)/0.08),1),round((((lijst[3]*3.3/1024)-0.52)/0.08),1)]

# lijst 0 is watersensor SB, lijst 1 is idem BB, lijst 3 is stroom SB, lijst 4 is stroom BB

# Turn on the SB pump if value > 510.    if (lijst[0]) > 510:
        GPIO.output(23,GPIO.HIGH)       #LED/pomprelais SB ON
    else:
        GPIO.output(23,GPIO.LOW)        #LED/pomprelais SB ON

# Turn on the BB pump if value > 510.
    if (lijst[1]) > 510:
        GPIO.output(24,GPIO.HIGH)       #LED/pomprelais BB ON
    else:
        GPIO.output(24,GPIO.LOW)        #LED/pomprelais BB ON

    print (data)

        #Output naar csv file
    #csvfile = "/home/pi/programs/testdata.csv"
    #with open (csvfile,'a') as output:
    #    writer = csv.writer(output, delimiter = ',' ,lineterminator = '\n')
    #    writer.writerow(data)
        
    time.sleep(0.5)

Now i will try to get a 4 x 20 LCD screen incorporated to display various values.
Should i do that in the same script or write a new one and somehow point it??

Tks Steffen