[U-Boot-Users] change U-boot file stream to COM2

Hello, I have an PXA270 bord with U-boot version 1.1.2 (Dec 22 2005 - 09:10:28) I want to change the file stream stdin and stdout to the serial COM port 2, now its on COM1 I tried with

-setenv stdin serial1 -saveenv

also tried with

-setenv stdin=serial1 -saveenv

but no luck. The file stream is always COM1. Can you gibe me a hint? Best regards