Maximum encoder speed?

Hello. First of all, sorry for my not good English

Recently I maked and installed rotary sensor with 80 positions (80 holes with a diameter of 2.5 mm)
image missing https://i.gyazo.com/99cecf41d4db21eff27896cdd0520ee0.jpg
image missing https://i.gyazo.com/9b6f4695b91a9ed689995f66dfc27cc6.jpg

The encoder has those parameters: image missing https://i.gyazo.com/db4aa033f1c7d6b23a549ffb921ff35c.png
Datasheet www.mouser.com/ds/2/307/EE_SX138_1010-8837.pdf

My problem is that it can not measure more than 200 revolutions, and I do not know why this happens.
I connected the sensor in parallel to the index and phaseA, and set in the settings of 80 cycles per revolution. Maybe it's because I do not have a separate index sensor?
In what else could be the reason in your opinion? Any ideas are welcome

I would take a look at the "A" signal with halscope to debug this

You do need a separate index signal for threading and tapping

Sometimes optocoppler are not very fast.

And that type of sensor has to be fully covered.

I'm using a similar disk, with 60 slots and it works fine up to 3000RPM (max of my spindle) thru the parport.
The only issue I had was that I made it from blue acyrilic, which seemed to be transparent to infra red. Spray of black paint fixed it. The other sensor you can see is the standard sherline sensor, which I'm using for the index pulse (the white tape on the disk!)


Sensor is exposed as seen in pic. Datasheet attached.
au.rs-online.com/web/p/slotted-optical-s...es/0304560/?sra=pstk