Thanks, Ed.

These are info about communication.

asynchronous stream,
no parity bit,
no handshaking

I coded as follows.
----------

Form.Init :

Thisform.Olecontrol1.ComPort=1
Thisform.Olecontrol1.Portopen=.T.

Form.Command1.Click :

Thisform.Olecontrol1.output=chr(0xaa)+chr(0x34)+chr(0x00)+chr(0x01)+;
chr(0x00)+chr(0x01)+chr(0x00)+chr(0x00)+chr(0x00)+chr(0x10)+chr(0x00)+;
chr(0x00)+chr(0xF0)

Form.Olecontrol1.OnComm :

if this.commevent=2
vcon=thisform.olecontrol1.input
thisform.edit1.value=vcon
endif

-------

The result is nothing. Nothing is in the edit box.

I think the problem is input. If the Input type is hex, is there something that I should do?

Also When I changed 0-Text into 1-Binary at InpuMode of MSComm, an error occurred. The Message is "Array dimensions are invalid".

Thanks for any advise.