pigpiod and reading seatalk. Can't make sense of the data

[jimseng]

Hello
I'm trying to interpret Seatalk data as per the optocoupler/pigpiod route as per this python script:https://github.com/Thomas-GeDaD/Seatalk1-Raspi-reader/blob/master/STALK_read.py
I can't make any sense of the data coming in, as in none of it seems to represent datagrams as described on this page: http://www.thomasknauf.de/seatalk.htm

I have created an interface using Marco Bergman's remote.py script and I am sucessfully able to send commands to my ST6000 autohelm so I know that the Seatalk data is being sent correctly (otherwise the auto-helm wouldn't respond).
However, like above when I am reading (verifying) data I have sent to the Seatalk bus, I can't make sense of the data coming back. It doesn't match what I am sending out. So with or without the boat Seatalk bus ruining if I send the auto or standby command:
#Auto
write_seatalk(b'\x01', b'\xFE')
#Standby
write_seatalk(b'\x02', b'\xFD')

def write_seatalk (xx,yy):

with serial.Serial() as ser:
	ser.baudrate = 4800
	ser.port = '/dev/ttyAMA1'
	ser.stopbits=serial.STOPBITS_ONE
	ser.bytesize=serial.EIGHTBITS

	ser.open()
	ser.parity = serial.PARITY_MARK
	ser.write(b'\x86')
	ser.parity = serial.PARITY_SPACE
	ser.write(b'\x11')
	ser.write(xx)
	ser.write(yy)
	ser.close() 

The response in my test script (which I have pared down to the bare minimum for testing purpposes:
st1read.bb_serial_read_open(gpio, 4800,9)
while True:
out=(st1read.bb_serial_read(gpio))
if out[0] >0:
print(out)
time.sleep(.1)

I get this response: (alternating b'\x01', b'\xFE', b'\x02', b'\xFD')

$STALK,1e,f7,ff,40

$STALK,1e,f7

$STALK,7f,81

$STALK,1e,f7,ff,40

$STALK,1e,f7

$STALK,7f,81

$STALK,1e,f7,ff,40

$STALK,1e,f7

$STALK,7f,81

$STALK,1e,f7,ff,40

$STALK,1e,f7

I have tried inverting the signal but it makes no difference. I can't see how that corresponds to the data I am sending out. Can someone suggest what I have missed?

[jimseng]

Well I must have failed to invert the signal. I thought I had got it right but obviously not so I'll just complete this thread by saying st1read.bb_serial_invert(gpio, 1) fixed it. The data makes sense now. Me making sense of it is another matter but baby steps.