Siemens G120 reverse problem

[Stasio]

Hello to everyone, a Siemens inverter Sinamics g120c just replaced an old danfoss.
Macro 18 is used for commissioning meaning two DI (pin5 & 6 ) for forward and reverse motor rotation.
External power supply for forward reverse commands with a plc.
Everything is working great except: ones in a while (especially at the startup) when the plc gives the forward command the motor rotates in reverse rotation!!!!!
Really really weird. Happened to someone before?
Any ideas?
Thanks in advance.
(already reset all parameters through Bop panel )

[CoMod]

by deafault in some inverter setting for direct rotate only.
Parameter Description
p1110[0] = 1 Negative direction of rotation is permanently inhibited.
p1110[0] = 0: Negative direction of rotation is enabled.

p1110[C] BI: enabled negative direction 0
p1111[C] BI: enabled positive direction 0

[Stasio]

Thanks man for your quick response.
Already tried parameter P1110 and the drive insists on going in reverse but only some times.
Maybe 99 times is turning forward and 1 time is going reverse.
Going crazy.
I even disconnected the reverse command from the drive (No 6 pin) just in case with no luck.
It only receives the forward command in pin No 5 and the machine worked the whole day but one time it turned in reverse again.
Now i had a full factory reset and i will let you know on Monday.
Thanks again.

[Dfcz]

Бывало (бывывало)) такое давным-давно.
Именно один раз из 10 при запуске двигатель "ехал не туда".
В моем случае параметры не соответствовали железу или не соответствовали нагрузке. Точно не помню, но вроде как у двигателя номенклатурный номер чуть-чуть не соответствовал заданному: слесари в ночную смену сняли и поставили с другой машины.

[Stasio]

Бывало (бывывало)) такое давным-давно.
Именно один раз из 10 при запуске двигатель "ехал не туда".
В моем случае параметры не соответствовали железу или не соответствовали нагрузке. Точно не помню, но вроде как у двигателя номенклатурный номер чуть-чуть не соответствовал заданному: слесари в ночную смену сняли и поставили с другой машины.

Thanks for your reply, do you remember the actual parameter that was causing the problem?

[Dfcz]

I do not remember. Sorry.
Look at the encoder resolution parameter.

[Dfcz]

I also recall a case when the encoder on the engine is loosely fixed. But that was on Simodrive.

[Stasio]

There is no encoder on the system.

[Dfcz]

If the system does not have a speed sensor, then sometimes it can rotate backwards only when the speed is too high for this system.