diff --git a/tests/query_device.py b/tests/query_device.py
index b63a0e5..ba272f0 100755
--- a/tests/query_device.py
+++ b/tests/query_device.py
@@ -4,7 +4,7 @@ from sys import argv,exit
 
 def print_help():
     print( \
-f'''{argv[0]} ADDR [BAUDRATE] [{{read [REGISTER ...] | write VALUE REGISTER}}]
+f'''{argv[0]} ADDR [BAUDRATE] [{{read [REGISTER ...] | write VALUE REGISTER | reset}}]
 where:
     - ADDR is Modbus address (use 0 for broadcast; note that only write can be broadcast)
     - BAUDRATE is (optional) baud rate; default value is 19200
@@ -30,6 +30,10 @@ Turn LED off for sensor 247, baud 115200:
     {argv[0]} 247 115200 write LED_on 0
 Set brightness of all connected sensors to 50%, default baudrate (broadcast message):
     {argv[0]} 0 write LED_brightness 50
+Reset device 247, baud 19200:
+    {argv[0]} 247 19200 reset
+Reset all devices, default baudrate:
+    {argv[0]} 0 reset
 ''')
 
 # default values
@@ -99,13 +103,13 @@ if action != 'write' and len(register_name) + len(register_number) == 0:
     input_registers = [ x for x in Sensor.input_registers.keys() ]
     holding_registers = [ x for x in Sensor.holding_registers.keys() ]
     register_name = input_registers + holding_registers
-if action != 'write' and addr == 0:
+if addr == 0 and action != 'write' and action != 'reset':
     print(f'Cannot broadcast action "{action}"')
     exit(-12)
     
 # Query device
 print('---- Query device ----')
-print(f'Address: {addr}\nBaudrate: {baudrate}\nAction: {action}')
+print(f'Address: {addr if addr != 0 else "0 (broadcast)"}\nBaudrate: {baudrate}\nAction: {action}')
 if action == 'write':
     print(f'Value to be written: {value}')
 # open device
@@ -150,8 +154,8 @@ elif action == 'write':
         print(f'Register number {reg_number} cannot be written')
         exit(-9)
 elif action == 'reset':
-    if not s.reset():
-        # reset should throw NoResponse; if it doesn't, reset failed
+    if not s.reset() and addr != 0:
+        # reset should throw NoResponse; if it doesn't, reset failed (broadcast shouldn't return anything)
         print('Device reset failed!')
     else:
         print('---- Device reset ----')