keyence bt-w250 serialport problem IO Exception

[imnotghost]

when i run this code at device MC3090 handheld that no problem . device will pop out bluetooth UI(UI from handheld) to let me connect.

dim Comport as new serialport
dim port as string () =serialport.getportnames
for i as integer = 0 to port.length
with
with Comport
.portname=port(i)
.open
end with
writeInPrinter() 'send command to printer by using Comport .write("Something")


but when i run in device keyence BT-W250GM it will cause ioexception(the status have the problem i think the status have open by handheld. but if handheld have connect to device . then how can i send command to printer and let printer write it out...what instance should i call for instead my comport.write... ).i have debug and this happening while open the comport. i have no any idea. anyone have kind of experience for solve this kind of model handheld? pls help me