Page published Jan. 15,
2011. If you have comments or
suggestions, I will be happy to hear about them.
Scotty. [wsprowls (a.t.) yahoo.com]
purpose of this page is
to describe the use of the Special Test, LPT-Printer Port Test. This
test will verify operation of the computer's Parallel Printer Port
and/or a printer cable connected to it. No
MSA hardware is required to perform this test. A voltmeter is
recommended for testing. Verification of the LPT can be
accomplished without one by using a jumper wire, and using a "Status"
pin to read a "Command" pin.
Set-Up for LPT Test:
1. Run the MSA Program.
a. If the Program has not been run before, the Hardware
Configuration Manager Window will open. Verify that the LPT Port
Address is Hex 378. If you know your LPT Port Address is different,
insert it. However, the LPT Test will run, even if the address is
wrong. Click "Save Configuration".
b. Otherwise, the MSA Main
Graph will open and
sweep with the MSA in the
Spectrum Analyzer mode.
3. Click menu item, Setup, and select Special Tests.
4. The Special Tests Window will open.
5. Click the "LPT Port Test" button.
6. A new window will open, "LPT Printer Port Test". It is divided into 3 areas.
Commanding is on the
left, Receiving is on the upper right, and Addressing is on the lower
7. The computer is now ready to
respond to your actions within this
Click either a "0" box or "1" box associated with a
particular pin of
the 25 pin Parallel Printer Port Connector. The value next to the pin
description will change, according to your selection. That pin on the
connector should measure approximately 0 volts for a command of "0",
and greater than +2.0 volts for a command of "1". An error here
indicates that the LPT Port Address in the MSA software is not correct
for your computer. Change the LPT Port Address in this "LPT Printer Port Test" window. See the paragraphs
following this Test Procedure. Assure Commanding is successful before
Click the "CAPTURE STATUS" button to read the
"Status" port of the
computer. If there is nothing connected to the 25
pin Parallel Printer Port of the computer, all status bits should
indicate "1". If they do not, the possible explanation is that the computer does not have
internal "pull-up" resistors. To test for this, measure the computer's
LPT Parallel port, pins 10 through
13, and 15 with a voltmeter. They should read +2.0 volts or greater. If
the computer does not have internal "pull-up" resistors, they
must be on the MSA's Control Board.
Even without internal "pull-up" resistors, you can still test the status pins
by using a "Command" pin as a signal source:
1. Connect a wire from pin 1 (Strobe) to pin 11 (WAIT).
2. Click the "CAPTURE STATUS" button to
read. The "Wait" box will display the state of "Strobe".
3. Change the state of pin 1 and then click the "CAPTURE STATUS" button to
read the state.
4. Move the wire. Pin 1 (Strobe) to pin 10 (ACK),
and repeat the actions.
5. Do this for pins 12, 13, and 15, using pin 1 as the signal source.
Exiting the LPT Test Procedure
Printer Port Test" window.
b. Close the Special Tests window.
c. Click the "Restart" button in the Main
MSA window. This will re-initialize the MSA software, and hardware if the
MSA Control Board had been connected during the LPT
the Addresses of the Computer's LPT port.
The computer has allocated 3 addresses for the LPT Printer Port. They
"Port", "Status", and "Control". You can "ask" your computer what they
are by following these steps:
From your computer's main window, click:
Start/Settings/Control Panel/System/Device Manager.
From there make selections similar to Ports/Printer
Port(LPT1)/Properties/Resources. Look for the item Input/Output Range,
which will display a range of numbers in Hex. The first number in that
range is the "Port" address of the LPT port. It is usually the address
of the LPT on the Motherboard. If an external Printer Port Card is
installed in your computer, it will usually be a secondary range.
The "Status" port is a value of "1" greater than the "Port" address. The "Control" port is a value of
"2" greater than the "Port" address. Changing the Addresses of the
address in the "LPT Port Address (Hex)" box is the "Port" Address that
is in the Configuration Manager. It can be changed during this test.
The value in the box is in Hexadecimal. But, you may insert a new
address in either Hex or Decimal (base 10). That is, the normal value
is Hex 378. The decimal equivalent is 888. If typing in a new value,
either the "Hex" box or "Dec" box must be clicked. If a decimal value
is entered, the displayed value will be converted to Hex when the "Dec"
box is clicked. This will not change the Addresses in the Hardware
Configuration Manager. You must do that manually via the menu,
Setup/Hardware Config Manager.