added python script to craft messages

test-msg-gen.py

@@ -0,0 +1,45 @@
+import binascii
+import struct
+import codecs
+
+print("Calculate NSPanel hex command from JSON payload\n")
+
+#value = input("Enter JSON:\n")
+value = "entityUpdHeading,Heading1234"
+
+def crc16(data:bytes, poly:hex=0xA001) -> str:
+    '''
+        CRC-16 MODBUS HASHING ALGORITHM
+    '''
+    crc = 0xFFFF
+    for b in data:
+        crc ^= b
+        for _ in range(8):
+            crc = ((crc >> 1) ^ poly
+                   if (crc & 0x0001)
+                   else crc >> 1)
+    return crc
+    
+
+payload = bytes(value, 'ascii')
+
+header = binascii.unhexlify('55BB')
+
+print("length:", len(value))
+
+length = len(value).to_bytes(1, 'little')
+
+bytes_payload = header + length + payload
+
+#print("bytes_payload:", bytes_payload)
+
+msg_crc = crc16(bytes_payload)
+
+#print('{:04x}'.format(msg_crc))
+
+crc=struct.pack('H', msg_crc)
+
+command=binascii.hexlify(bytes_payload + crc)
+
+print("\n\n")
+print(bytes.decode(command))