Serial communication problem with 6 linear axes

HI .
I'm using marlin 2.0 , bugfix version for my 6 axes robot (not a 3D printer ) + MKS GEN v1.4 motherboard + MKS TFT32 . TFT firmware is open source Bigtreetech . Serial port is 0 with 115200 baudrate and I'm using AUX 1 of MKS GEN v1.4 motherboard for TFT32. of course Serial communication in pronterface program established without problems in all cases .
when I define LINEAR_AXES 3 , everything is ok but when I define LINEAR_AXES 6 and set depended configs , mks tft 32 will disconnect and show "NO printer attached" message .
What tests did I take ?
Upload marlin with original configurations ( just change motherboard and baudrate) ==> everything is OK
Several baudrates and serial ports ==> "NO printer attached" message
Several pins definition for 6th axis ==> "NO printer attached" message

I think the main problem is additional axes and cause disconnection .

can anyone help me with this issue ?
thanks and sorry for my English !!

... pins mismatch/redefines?

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Viktor
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Thanks for reply . No I'll check this out before. In the last test I did last night, I came to a strange conclusion. When I activated five axes with an extruder, the problem of serial communication with the display was also solved. Then I tested the sixth axis with an extruder and everything was right.
For now, I have to activate an additional extruder to solve this problem and use futile digital pins to define extruder driver pins.
What do you think about this?
It was strange for me, too.

Edited 1 time(s). Last edit at 08/09/2021 02:26AM by jafar_niknam.

pins file? Config files? for your 6 axis tests.

They have open a github issue with needed files.[github.com]

Thanks for reply . yes you can see config files in github .
Did you check the files? Do you think it's a problem with the display or Marlin ?

Since you can use the serial port via a control program without issues, its a display issue