[WriteLog] HAL DXP38

[Tom McDermott]

Hi Ken,

	A couple of possibilities...

1) A lot of laptops have fairly poor RS-232 drivers. These may not swing
negative to ground very much. Long time ago, the swing was plus and minus 15
volts, then sort of became plus and minus 6 volts, then became +6 volts and
sort of ground. In addition, some laptops could no longer drive the amount
of current required by RS-232, so for example the load resistor was way, way
beyond the laptop's driver capability. I've tested several laptops that are
incapable of sucessfully driving a 2.2K resistor.

   You probably want to look at the voltage swing to make sure that the
DXP-38 is happy.  The DXP-38 should drive any computer or laptop OK -- it's
the direction from laptop to DXP-38 that could be an issue.

2) Some laptops are not very careful about obeying the RTS, DTS, CTS. DCD
voltage levels, or signaling states. The 25-pin to 9-pin converters needed
for laptops may not provide all the levels that the DXP-38 requires to
operate (I've not used the DXP-38, just the HAL P-38, so more experienced
people would have to verify the DXP-38 requirements...).

	-- Tom, N5EG





------------------------- Ken wrote ------------------------
Hi,
Any thoughts or help will be appreciated with this problem.

We have 2 Dell Laptops with windows 98, Writelog 10.42. The TNC's are both
HAL DXP38. For some reason the DXP38's will not connect with Writelog. No
rcv or xmt. However, the TNC's work with a machine with Windows XP. So we
know the TNC's are working. But absolutely nothing on laptops.
Any suggestions?
73 Ken W0LSD