[WriteLog] WL - Serial Cables & radio interfacing

[Dick Green]

Bob,

Good general summary, but a couple of corrections:


> 3.)  Once you have the right cable, you should get some response
> out of the rig.  Be sure to power on the radio BEFORE running
> Write Log.

This is not necessary with my FT-1000MP or FT-990. This is probably
brand-specific.


> Also be SURE that the SETUP PORTS menu in Write Log
> is set for ONLY ONE FUNCTION for each of your serial/COM ports.
> That is, a single port may be used for rig control, sending CW,
> doing packet or antenna rotor control - BUT NO TWO OR MORE OF
> ANY OF THESE!

There is one case where this is not true: the W5XD+ external keyer can share
a COM port with a rig. In this case, you check both the CW radio button and
check the Rig box for that COM port.

> 4.)  Finally, the design architecture of the PC causes some
> strange results when you attempt to use more than two COM
> ports because of the sharing of hardware interrupts.  Without
> getting too technical, be aware that often devices that use
> COM 1 and COM 3 may not work simultaneously because they share
> IRQ 4.  Likewise, COM 2 and COM 4 devices share IRQ 3 and may
> not work simultaneously.  To check this out, get all your
> Write Log devices working ONE AT A TIME.  Once you achieve
> that, then try to use them simultaneously.
>
> Many times an internal modem that is used to access the
> internet won't function properly with Write Log running.
> In fact on my machine, I get a "SERVER FUNCTION FAILED"
> error message from Write Log if I go online while my radio
> is interfaced.  The cure is to assign a different interrupt
> (IRQ) to COM 3 and COM 4 but this requires both hardware and
> software that will allow you to do that.  Often some devices
> will work OK because they don't generate interrupts but I
> don't know how to tell in advance without simply trying it.

In theory, shared interrupt conflicts are not supposed to happen in Windows
98 (and maybe Windows 95, but I'm not sure.) Windows 98 is designed to
handle shared interrupts transparently to applications. This really isn't
all that hard to do. When an interrupt occurs, the OS simply looks at each
COM port to see which one has received data ready or has encountered a
handshaking signal that generates an interrupt. The data or state change is
queued up to be given to the application when it resumes execution. There
should be no problem if both ports generate an interrupt at the same time --
the OS should check each device configured to use that IRQ and queue
whatever needs to be sent to the associated application. I have several
devices that share interrupts on my system, including four USB COM ports and
an internal modem that shares interrupts with the soundcard. They all work
nicely together.

Now, with that said, there certainly could be bugs in Windows 98 or drivers
that came with add-on COM ports that prevents proper operation. Also, if an
application attempts to directly mess with a COM port (like resetting the
IRQ line), this can cause problems.

73, Dick WC1M


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