Serial
Port Expansions
by
Dick Stevens, N1RCT (with much help )
For a basic understanding of RS-232 ports,
check out the fine tutorials on:
hhttp://www.u-net.com/epr/electron/issue1/feat0710.htm
Bruce, WT4I has a webpage describing how the Byte Runner expansion card is used in his shack with Windows 95. http://www5.palmnet.net/~wt4i/ComPort.html
Wayne, W5XD, has a web page on Com Ports: http://www.contesting.com/writelog/support/irqs.htm
Byte runner has the best info on how to add more than 4 com ports
to WIN95 or Win 3.1:
http://byterunner.com/tech.html
I took the recommendation of Jeff K1AM
and bought the Flexport 42, the 4 being the number of serial ports and
2 the number of LPT (parallel) ports. I don't know if I will ever
need the LPT ports, and a Flexport Model "4s" is available without
the parallel ports. The card has a single large connector on the back,
a bit bigger than a normal 25 pin RS-232. The card comes with a "spider"
cable which has the big plug on one end and four DB 9 male (the little
ones) connected to it via cables abt 50 cm long. I then visited Walmart
for cheap cables with 9 pin female at one end, over to Radio Shack for
some 9 pin plugs and shells for hand wiring, and all the way to Dayton
to get some 25 pin female to 9 pin female adapters. Between all this, I
got all my acessories wired up to 9 Pin. Here is a picture of the card
out of the computer:
Click here for BIG picture of Flex42 Card
The Flexport 42 is easy to set up once you know exactly what else is hooked up on your computer, such as sound card, CD-ROM, ethernet, modem, anything that uses an IRQ and address. I put it all on a post-it note attached to the monitor. My post-it for computer 1 (EIDE/VLSB bus)reads:
Device IRQ
Address
Sound
10 3F8
IDE
Cont. 14 -
CD-ROM 15
170
&COM1 Mouse
4 3F8
&COM2 Kenwood 3 2F8 (this
is the MFJ 5383K converter cable)
*COM3 K6STI FSK
4 2E8 (IRQ
conflict OK with RITTY)(home made box and cable)
*COM4 PK900 5 2E8
*COM5 WF1B Net 11 100
(a null modem
cable; see the manual or the RS232 tutorial)
*COM6 KPC3 TNC 12
180
For Computer 2 (PnP PCI bus), it reads:
Device IRQ
Address
Sound
7 3F8
IDE
Cont. 14 -
CD-ROM
7 170
&COM1 Mouse
4 3F8
&COM2 Icom 3 2F8 (MFJ
5383I converter cable)
COM3 unused - -
COM4 Inet Modem 5
2E8
*COM5 WF1B Net 11 100 (the
other end of the null modem cable)
*COM6 PK232 TNC 12 180
*COM7 Free 15
290
*COM8 Free 10 340
& = Existing Port
* = Flexport 42 plug
It is harder to tell what is going on with a Plug 'n Play mother board; I guess they don't want to confuse the average user. First of all, the Flexport does not care what you call the ports; they are labeled A, B, C, and D in fact. However most software will often make assumptions; if you say a device is connected to COM 2, it will assume it is the standard default values of IRQ and Address and may not even permit you to change. So for COM3 and COM4, best to stick with "default" values for addresses but new IRQ values are needed as the defaults are the same as COM1 and COM2. When using WF1B Ver 3, the only significance of the COM port number is to identify the same port to the [TNC] and [SerialPort] sections in RTTY.INI. All IRQ's and Addresses are available under WF1B, but conflicts can still occur! In general, all ports must have a unique IRQ and Address with very few exceptions.
The standard addresses for COM1-COM4 are given under Computer 1 above. There are no standards for IRQ or Address for COM5-COM8 yet. The Flexport 42 provides the standard addresses plus 4 more (340, 290, 180, 100). It provides all IRQ's. BTW, the addresses are normally "Hexadecimal" numbers and are designated as such to WF1B by preceeding with a dollar sign such as $180 . Other programs often put a 0 in front and maybe an "h" at the end such as 02E8h; and some demand only decimal equivilent such as Lan-Link. The Windows calculator utility will do conversions when in the scientific mode. Hexadecimal 180 is decimal 384, for instance. You must be able to do this in your head before continuing . (just kidding). What these Address numbers really are is the location in a special "system memory" area where its input/output data and status is stored for use by the microprocessor. The IRQ is one of several physical signal lines that says that new data has arrived for the microprocessor to use. The unique number is required so the microprocessor knows which port/device is asking for attention.
The key to a smooth
startup with extra Com ports is knowing exactly what you already have in
use. Then the 4 new ports are assigned unique addresses and IRQ's. The
most reliable IRQs are 5,10,11,12, and 15.
Your sound card, CD-ROM, and modem may have used up three leaving 2 IRQ's
for 4 Ports, a distinct problem. My six ports are easy on Computer
1 because: 1. no modem and 2. RITTY FSK never activates it's
IRQ so it can be assigned the same as the mouse. On computer 2, the sound
card is able to work on IRQ 7 and the CD-ROM goes into the PCI bus directly
without an IRQ needed (apparently), again giving 4 good IRQ's available
for the Flexport (10,11,12,15).
IRQ's 2, 6, 8, 9, 13, 14
will probably not work at all for any device;
IRQ's 3 & 4 are probably in use
for the normal COM 1 and COM 2 ports, unless you have a bus mouse. (The
MSD DOS Utility gives the purpose of these IRQs for the truely inquisitive.)
Be prepared for some trial and error work on getting things to work although
I got lucky and it worked the first time.
After deciding what addresses and IRQ's will be used, and what COM port you choose to call the A,B,C,and D plugs, just change the jumpers on the card (no software here). Then label each port with the COM number you chose to call it. (I was able to use COM 3-6 on computer 1 and COM 5-8 on computer 2). You should avoid calling it COM3 if you already have called your modem COM 3, for instance. Next, mark the cables of all your accessories with the name of the device it goes to. Believe me, when you have six ports on each computer, it is impossible to remember which is which. I checked each port by using Log-EQF to a PK-232. Log-EQF has a quick-change menu for all all IRQ's, addresses, and COM port numbers. You should use a device and program that you have high confidence in to check out each port.
So things are all hooked up ... time to make
the changes in RTTY.INI to specify your new equipment and ports. Just follow
the manual! If you find some new solution, please let me know
so we can add it to this material. Other setups and needs will lead to
other solutions!
My Flexport 42's came from:
HDSS (800-252-9777) in Newark, CA and cost $US 99 / each but here
is a caveat from Dave, WW2R:
"I purchased one 8 weeks ago from
this crowd and am still waiting for it..as of 9/1 there 1-800 # is u/s
there non 800 number is disconnected and the people at their last known
address answer in spanish denying they have ever heard of them. I gather
they were bought out and "lost " all outstanding order issues"
There are probably less expensive solutions around; let's hear about your
find and we will add it here. Just think of how you want your station to
be a year from now before deciding on the cards. If you
know of a good way to check out COM Ports, please let me know and I will
get it added here. 29 May '97
I like questions, comments, suggestions, and
tips for inclusion in these tutorials; E-Mail
me Now!
73 de Dick, N1RCT
I received this clever setup from Bob Lewis AA4BP which could be all you
need .. basically, it duplicates IRQ's but does not use programs that use
the conflicting devices at the same time. For an expansion card, a regular
el cheapo I/O controller card was used set to COM 3 and 4; the IRQ's are
not adjustable. Thanks to Bob for sharing it.
Date: Fri, 20 Jun 1997 16:24:22 -0400
From: Bob Lewis
<aa4pb@erols.com>
Subject: Com Port Sharing
I also have COM2 and COM4 both set to IRQ3.
COM2 is the HF transceiver and COM4 is the Pactor Controller. These two
are never used at the same time. When I load my PacketCluster software,
it talks to the TNC on COM1 and the HF rig on COM2 (different IRQs) so
everything is cool. Total resource usage is 4 COM addresses and only two
IRQs.
On the Packard Bell 486SX/15 I used the two ports on the motherboard
plus a "no-name", $15, add-in card and a Cardnal modem. On a
home-assembled pentium 166 I have used the motherboard ports, sharing IRQ4
with COM1 and a Cardnal 33.6 modem. I used Window 3.1 and Windows 95 on
the 486 and Windows 95 on the pentium.
The modem and TNC software are Windows programs
(although I never multi-task them). The Pactor and packet cluster software
are DOS programs which I run exclusive in a DOS window or directly in DOS.
In Windows 95 I have to go into the Control Panel, System, Device Manager
and force the settings for the ports and modem (no plug-and-play).
On the pentium, the bios also gives
me the option of setting the two COM ports as "legacy" devices
rather than "plug-and-play". The Device manager reports an IRQ
conflict when I do this but it works okay because I make sure the two ports
are never used at the same time.
73, Bob (AA4PB)
Subject: Sharing IRQs update 18 Nov '9
I recently purchased and installed a new Hayes 56K flex internal modem card and you guessed it - it won't share an IRQ with anything. It always disables the IRQ for the shared device even if the modem is not being used. I assume that this has to do with some type of totem pole circuit in the modem's IRQ output holding the IRQ in the normal state even though the shared device is trying to trigger it. This is the first serial device that I have run across that gives this problem.
73, Bob (AA4PB)
Here is another source of I/O cards:
Subject: Serial I/O Card
Dick, I really enjoyed your articles on the serial cards and have
been looking around for a few months now for a inexpensive card. The company
in Knoxville, TN has gone up on their price, so I continued to look elsewhere.
A friend of mine told me that he call one of our advertisers "DEBCO"
and they were selling some of their older cards for $10.00. I bought 4
this afternoon, two ISA and two VESA. Just thought you might want to include
this in your article on serial ports and cards. These cards have 4 serial
and 2 parallel ports. List price is $129.95 MCT-AMS+. 1-800-423-4499
73 de Nick, WA4GKM
