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« on: June 12, 2023, 03:20:11 pm »
There are a few issues. The connection should be RS232 not TTL. So you need a USB to RS232 adapter not USB to TTL.
I tried my USB/TTL and got the same result you did. So, I checked the schematic and noticed it shouldn't be TTL and also the pinout in the schematic is different from the manual.
In the manual pin numbers alternate rows. So, ground is the bottom right most pin9 (pin 5 in schematic).