diff --git a/tests/find_address.py b/tests/find_address.py
deleted file mode 100755
index c201ebf..0000000
--- a/tests/find_address.py
+++ /dev/null
@@ -1,35 +0,0 @@
-#!/usr/bin/env python3
-from time import sleep
-from sys import exit
-import minimalmodbus
-import serial
-
-
-print('---- Looking for device ----')
-slave_address_list = range(200,256)
-baud_list = [19200,115200]
-CO2_addr = 9
-total_devices = 0
-for slave_address in slave_address_list:
-    for baud in baud_list:
-        print(f'Address {slave_address} baud {baud}:\t\t', end='')
-        try:
-            # modbus init
-            instrument = minimalmodbus.Instrument('/dev/rs485', slave_address, close_port_after_each_call=True)  # port name, slave address (in decimal)
-            instrument.serial.baudrate = baud
-            instrument.serial.bytesize = 8
-            instrument.serial.parity   = serial.PARITY_EVEN
-            instrument.serial.stopbits = 1
-            instrument.serial.timeout  = 0.05          # seconds
-            instrument.mode = minimalmodbus.MODE_RTU   # rtu or ascii mode
-            instrument.clear_buffers_before_each_transaction = True
-            ##
-            CO2 = instrument.read_register(CO2_addr, 1, functioncode=4) * 10
-            print('DEVICE RESPONDED')
-            total_devices += 1
-        except minimalmodbus.NoResponseError:
-            print(f'no response')
-        sleep(0.1)
-print(f'Found {total_devices} devices (tried {len(slave_address_list)} addresses)')
-print('---- DONE ----')
-exit(0)
diff --git a/tests/find_device.py b/tests/find_device.py
new file mode 100755
index 0000000..dea07f9
--- /dev/null
+++ b/tests/find_device.py
@@ -0,0 +1,94 @@
+#!/usr/bin/env python3
+from time import sleep
+from sys import exit, argv
+import minimalmodbus
+import serial
+from sensor import Sensor
+
+def print_usage():
+    print(
+f'''
+USAGE:
+\t{argv[0]} [ -a [{{FIRST_ADDR-LAST_ADDR | ADDR}} ...] ] [ -b [BAUD ...]]
+EXAMPLES:
+Complete search (slow!):
+\t{argv[0]}
+Look for devices 123,10,56 at baudrates 19200,115200:
+\t{argv[0]} -a 123 10 56 -b 19200 115200
+Look for devices 10-55 at baudrate 19200:
+\t{argv[0]} -a 10-55 -b 19200
+Look for device 1-10 and 55 at baudrate 115200:
+\t{argv[0]} -a 1-10 55 -b 115200
+Look for device 1-10 at all possible baudrates:
+\t{argv[0]} -a 1-10 55
+'''
+            )
+
+# Parse arguments. And no, I won't use argparse.
+processing_address = 0
+processing_baud = 0
+addr = []
+baud = []
+for arg in argv[1:]:
+    if arg == '-a' or arg == '--address':
+        processing_address = 1
+        processing_baud = 0
+    elif arg == '-b' or arg == '--baudrate':
+        processing_address = 0
+        processing_baud = 1
+    elif processing_address:
+        if arg.count('-') == 1:
+            # range in form START_ADDR-STOP_ADDR
+            start_addr, stop_addr = arg.split('-')
+            for a in range(int(start_addr), int(stop_addr) + 1):
+                addr.append(a)
+        else:
+            addr.append(int(arg))
+    elif processing_baud:
+        baud.append(int(arg))
+    elif arg == '-h' or arg == '--help':
+        print_usage()
+        exit(0)
+    else:
+        print(f'Unknown argument {arg}')
+        print_usage()
+        exit(-1)
+# if empty, use all possible values
+if not baud:
+    baud = Sensor.baudrates
+if not addr:
+    addr = [a for a in range(1,248)]
+    addr.reverse() # we usually use high addresses for test devices
+# print
+print('---- Searchspace ----')
+print(f'Addresses: {addr}')
+print(f'Baudrates: {baud}')
+# search for device
+print('---- Looking for device ----')
+total_devices = 0
+tried_devices = 0
+CO2_addr = Sensor.input_register_offset['CO2_addr']
+for a in addr:
+    for b in baud:
+        print(f'Address {a : >3} baud {b : >6}: ', end='')
+        try:
+            # modbus init
+            instrument = minimalmodbus.Instrument('/dev/rs485', a, close_port_after_each_call=True)  # port name, slave address (in decimal)
+            instrument.serial.baudrate = b
+            instrument.serial.bytesize = 8
+            instrument.serial.parity   = serial.PARITY_EVEN
+            instrument.serial.stopbits = 1
+            instrument.serial.timeout  = 0.05          # seconds
+            instrument.mode = minimalmodbus.MODE_RTU   # rtu or ascii mode
+            instrument.clear_buffers_before_each_transaction = True
+            ##
+            CO2 = instrument.read_register(CO2_addr, 1, functioncode=4) * 10
+            print('DEVICE RESPONDED')
+            total_devices += 1
+        except minimalmodbus.NoResponseError:
+            print('no response')
+        tried_devices += 1
+        sleep(0.1)
+print(f'Found {total_devices} devices (tried {tried_devices})')
+print('---- DONE ----')
+exit(0)
diff --git a/tests/sensor.py b/tests/sensor.py
new file mode 100644
index 0000000..8060f04
--- /dev/null
+++ b/tests/sensor.py
@@ -0,0 +1,20 @@
+class Sensor():
+    baudrate_config = [ 19200,4800,9600,14400,19200,28800,38400,57600,76800,115200 ]
+    baudrates = [ 4800,9600,14400,19200,28800,38400,57600,76800,115200 ]
+    input_register_offset = { \
+            'CO2_addr': 9, \
+            'T_SHT4x_addr': 10, \
+            'RH_SHT4x_addr': 11, \
+            'T_SCD4x_addr': 12, \
+            'RH_SCD4x_addr': 13, \
+            'T_SHT4x_signed_addr': 14, \
+            'T_SCD4x_signed_addr': 15 }
+    holding_register_offset = { \
+            'LED_on_register': 0, \
+            'LED_brightness_register': 1, \
+            'LED_smooth_register': 2, \
+            'CO2_alert_limit_1_register': 3, \
+            'CO2_alert_limit_2_register': 4, \
+            'SCD4x_temperature_offset_register': 5, \
+            'MODBUS_address_register': 6, \
+            'baudrate_register': 7 }