Error on port COM1 using MS-DOS

Apr 18, 2018
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i have a PC running MS-DOS 6.22 . Sending data via serial port with the command:
echo 55 > COM1
always give the error:
Write fault error writing device com1 Abort, Retry, Ignore, Fail?

But if i write data directly on the serial port address (with Debug.exe) or i am using a linux live CD i can transmit data to another pc (with a basic null-modem cable). Is this normal? What can be the problem?
 

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