The GET TTLPOL command in the Lumencor spectra II is supposed to reply with POS or NEG for negative or positive polarity for the TTL input. However, it instead replies with 0 (for negative) and 1 (for positive).
>> print(serial.write(b'GET TTLPOL\n'))
11
>> print(serial.readline())
b'A TTLPOL 1\r\n'
While the manual (Document Number 57-10018 Revision B 010319) clearly states that:
Get TTL inputs polarity (positive or negative).
Command:
GET TTLPOL
Answer:
A TTLPOL POS