Air 420 software packages


If you are having blue screen crashes on the A420 PC see This Page

You need only download and run this one setup.exe file to install the software.
This file may be copied to a CD or moved onto the target PC by any means of transferring files. 
As of 9.3.47 we now support installing only on Windows 7, or 10 32 or 64 bit.  If you need to reinstall on older versions of Windows, contact Keiser support for an older version of the installer.  The online software update will work correctly with any version of Windows workstation newer than Windows 2000 other than Xp 64 bit.  The A420 software will look work and operate the same on any version of Windows 2000 or newer.  Installers downloaded before September 15 2019 may cause some versions of Windows 10 32 bit to crash and not be bootable.  Should you encounter this situation, the solution is to boot Windows 10 into safe mode and uninstall A420 from there.  If you are updating an older install to Windows 10, we recommend the following procedure.
1.  Update the version of A420 on the PC first.  Connect PC to internet, click on Help -> Check for updates
2.  Make a copy of the C:\A420 folder to external media such as a CD, USB mass storage or portable hard drive.
3.  Install Windows 10, overwrite existing installation.  Everything on the A420 PC hard drive will be over written.  This is the reason for step 2.  While an inplace update is possible, in testing we have encountered enough difficulty that we do not recommend doing so.
4.  Install A420 software with downloaded file from this web page.
5.  Device drivers for all the different serial add in cards we have shipped with A420 are located under C:\A420\Drivers
We have tested A420 on Windows 10 with the Titan brand serial cards which are marked PCIe-200 and is the device that has been shipping for the past year or more.  Windows 7 tested drivers for the older cards are available in the Drivers folder, however we have not tested any of these with Windows 10, they may or may not work.  The VSCOMM serial cards that were shipped with A420 at some point in the past are out of production and no longer available.  If you encounter difficulty making VSCOMM cards work with Windows 10, contact Keiser service to purchase one of the Titan cards.

6.  Copy the backup made in step 1 back over C:\A420\ folder.  You now have all your data back in place and are ready to go.

If your A420 PC is connected to the Internet, it will download and install updates automatically.  If you need support an internet connection is necessary for service to assist you.  If you are behind a firewall, only a connection to the domain is required.


The A420 manual is available as a separate download via the following link.   This manual is included in the setup download .


Download links     

A420 Manual
A420 Release 9.3.50 setup.exe file 

Instructions for replacing an A420 processor box

The setup file will install the latest manual on your computer.  Previous versions of the manual will remain in place.  You may delete the older versions of the manual if you wish.

WARNING this file is large (over 25 mbytes) and will take a long time to download on a slow connection!

Released Version History

Release 9.3.49 adds models 1133 & 1232, cosmetic changes to graph UI

Release 9.3.50 removes six rep test, many cosmetic improvements to graphing, adds autosave of summary data.

Release 9.3.49 adds models 1133 & 1232, cosmetic changes to graph UIRelease 9.3.49 adds models 1133 & 1232, cosmetic changes to graph UI

Release 9.3.48 fixes chip code used for diagnostics.  There are no noticeable changes to main
a420 program.

Release 9.3.47 drops installers for Vista and older.  These were causing problems for Windows 10 after recent Windows updates.

Release 9.3.46 adds drivers for Titan serial card

Release 9.3.45 Corrects visibility of "Percentage excluded" option in cases where outliers options are other than filtered.

Release 9.3.44 Adds option to invert bottom axis on variable test chart

Release 9.3.43 Makes data in the summary save data file have lots more decmal places for those who get confused by spreadsheets

Release 9.3.42 Adds new features to PC display summary data, adds go to rep button to graph chart.  Improves screen initial size handling for those with high resolution screens (2k 4k)

Release 9.3.41 Corrects a situation where an error would be detected and all air dumped after going through the cylinder calibration process.

Release 9.3.40 Adds drivers for newer version serial cards to install image.  Corrects a bug where an error message would be hidden in an all black label on Windows 7 with Aero enabled.

Release 9.3.38 Changes to make exercise machines increase resistance settings when a machine has not been used for some time to prevent compressors from running when machine is not in use.  Reps counted when no key is inserted will now reset to 0 after 60 seconds on non-use.

Release 9.3.37 Cosmetic changes to setup for use during manufacturing, not released to the public

Release 9.3.36 Changes to Variable test chart graphs to display reps with velocity greater than estimated max.  This situation will only occur in the case of an improperly completed 10 rep test.  This change makes detecting that situation easier.

Release 9.3.35 Changes to make graph screens look better on a PC using DPI settings other than the default 96dpi, laptops or those with 4k monitors.

Release 9.3.34 Adds more per user data and input editing.  Corrects bug where Internet update downloads could interfere with data saving.  Improvements for use in an environment where multiple ten rep tests are being conducted.

Release 9.3.30 Corrects a bug where displayed starting resistance per rep on 10 rep tests would not always display correctly.  This version will display correct results on data collected with an older buggy version.

Release 9.3.29 Cosmetic improvements to screen appearance.

Release 9.3.28 Cosmetic improvements to screen appearance.  Adds manual outlier controls on 10 rep data graphs. 

Release 9.3.27 Changes behavior of software update warning message after PC has not been used for a long period
.  No functional changes.

Release 9.3.26 Updates the installer to work on Windows 10
.  Fixes an issue where the 9.3.25 installer would install an incorrect version of the Pressure module.  Internet update would subsequently fix the problem.  The machine will work correctly in spite of this issue.

Release 9.3.25 Fixes an issue with automatic Internet updates that reported an error when software was up to date
.  No changes to function of the software.

Release 9.3.24 Adds display of starting resistance for each rep of a ten rep test
.  Improves operation of air valves when large changes in resistance are made, valves now make much less noise.  Adds support for a new design valve block.

Release 9.3.23 A420 will now install on Windows 8.1 as a viewer.  With this release we no longer will install on Windows 2000.  Automatic updates will still function on Windows 2000.  If you have an older system and need to reinstall on Windows 2000, contact Keiser service for version 9.3.22.  The A420 software functions exactly the same on all versions of Windows.  There have been no changes to the actual software with this version.

Release 9.3.22 Changes graph options for the ten rep test to remove the possibility of creating confusing invalid graphs.  Cosmetic improvements to Variable Test Chart graphics.

Release 9.3.21 Corrects a bug that causes some parts of Windows to get ahead of others and cause the PC software to crash.  No new features, no changes to the exercise machine.

Release 9.3.20 Adds three new features.  1.  Data window for current exercise opens automatically when exercise is done.  2.  A new bar is added to "By Rep" chart indicating the difference between left and right sides on Dual machines.  3. Automatically opens a new chart when data from a Ten Rep test is opened.  This chart plots the power line for up to 7 Ten rep tests that have been opened.  This chart is intended to compare results for multiple subjects.  These new features are not documented in the current manual.  An updated manual will be included in a future release

Release 9.3.19.  Brings access to the manual into the menu in the PC program, also by pressing F1 while program is running.  Update installer improves operation across various versions of Windows.

Release 9.3.18.  Updates the installer.  This version is back to a single installer for all versions of Windows.  The installed software has not changed since 9.3.15.

Release 9.3.17.  An update to the installer.  Since version 9.3.15 some versions of windows would do a clean install complaining about the Windows version being Win95.  This version has seperate installers for Windows 2000 and Windows XP.  The running software is unchanged since version 9.3.15

Release 9.3.16 Cosmetic improvements.  Velocity scales to fit the screen better on some graphs.  A rare error in older data files is handled more gracefully.  Only changes PC software, no machine updates.

Release 9.3.15 adds support for Windows 8. On line automatic updates from Windows 7 now operate correctly.  No change in software.

Release 9.3.14 makes a small change to make recovery from a rarely seen software bug occur without having to restart the machine.

Release 9.3.13 updates drivers for high speed serial card on Windows 7.  This change only effects new units shipped from the factory/

Release 9.3.12  Corrects a bug introduced by 9.3.11 which causes Velocity data axis scales to be much too large when displaying data in the Metric units mode.

Release 9.3.11 Corrects a bug that shows a chip as having a time stamp in the future when it is in fact ok.  Updates cosmetic look and feel issues on the graph screens of the PC program.

Release 9.3.10 Corrects a bug that would show only if trying to update an eChip time set key with A420 software.  No functional changes.

Release 9.3.9 Makes cosmetic changes to the look and feel of some graphic elements on the PC screen.  No functional changes.

Release 9.3.8 Corrects a minor bug in code intended to find errors in corrupted data files.  It is unlikely that anyone has seen any effects of this bug, however we correct it just to be safe.

RRelease 9.3.7 Detects time being set wildly incorrect on the PC and prevents the PC program from running in that case.  Previous versions would display a "Range Check" error and operate incorrectly.

Release 9.3.6 Corrects a bug in handling of ten rep test data on single cylinder machines which was introduced in 9.3.4.  A small change in the maximum displayable acceleration on certail models of machines to improve readability.

Release 9.3.5 Improves function of automatic update.  Reduces minimum force on Leg press and Rack.  Fixes an improper title for units on rotary machines.  Improves handling of data collected with older versions of the software.

Release 9.3.4 Makes rack work one side at a time.  Cosmetic, but nice layout improvements to the summary data screen on the PC.  PC software will now install on Windows 7-64 and Vista 64 as a file viewer. 

Release 9.3.3 Corrects a situation where the seat position indicators on the machine would not blank when a key is removed.  The index in the manual now has clickable links.

Release 9.3.2 Makes minor changes to improve service functions.  No operational features change.  If you have already installed 9.3.0 or greater and your A420 PC is connected to the internet, this version will automatically install.

Release 9.3.1 Improves some error messages in the automatic update feature.  Replaces the manual embedded software update program with a version that gets along with the automatic version better.  The previous release download inadvertently included an older version of the manual, the correct manual is included in this release.

Release 9.3.0 Makes the machine work without needing a key as a regular exercise machine.  Adds automatic updates over the internet.  Automates installation of embedded software on the exercise machine.  Power displayed on the exercise machine more closely matches the numbers produced by our regular power machines.

Release 9.2.10 Improves prompts on remote model set commands.  This update makes changes that only affect servicing the machine.  Functionally identical to 9.2.9.  Message strings from very old data on previous versions may incorrectly identify 10 rep tests as 20 rep or vice versa.  This update will only affect data collected many years ago.

Release 9.2.9 Corrects incorrect version message.  If you have installed 9.2.8 and are getting an incorrect firmware version warning, this release will correct that situation.

Release 9.2.8 Updates to match chip system software, A420 part unchanged.

Release 9.2.7 Makes changes to time handling related to chip system, A420 part unchanged.

Release 9.2.6  This release contains code that allows keys that are used in both A420 and the Keiser Chip system to co-exist with less interaction.  If you are not using the keys in both A420 and Keiser Chip system machines, this release is equivalent to 9.2.5 

Release 9.2.5 Changes handling of chip serial to user indexes to reduce the risk of index corruption due to concurrent access by more than one process.  Adds the ability to delete a chip out of the index.  This release has been tested on Windows 2000, Windows XP, Windows Vista and Windows 7 32 bit versions.  64 bit versions are not supported at this time. 

Release 9.2.4 Fixes a bug that caused data from the right side to be lost if multiple 10 rep tests are done in rapid succession.  Adds automatic prompt for a user name when a new un-named key is inserted into an exercise machine.

Release 9.2.3 Is compatible with restricted Windows user rights.

Release 9.2.2 Changes some text on various graphs displays for clarity.  Adds the ability to control and save default settings for graph screens.  + More

Release 9.1.4 This release improves display of error messages only on single cylinder machines.   It is identical to 9.1.3 for all 2 cylinder machines.

Release 9.1.3 Makes the chip operation more closely match that of stock Keiser Power machines.  Improves operation of the Iron Weight function on rack models. 
Adds model 1337 chest press. 

Release 9.1.2 Fixes a bug in calculating average data per rep, improvements to error handling on certain corrupt data files.  The bug involves situations where a different number of reps were done on both sides  of a dual cylinder machine where right side data would be incorrect beyond the point that reps no longer match side per side.  If data files are opened with this version, the proper results will display.  Only the software on the PC is updated here, the software in the exercise machine remains unchanged from the previous release.

Release 9.1.0 Adds support for rack models, many other improvements, see the manual.

Release 9.0.0 Adds support for installing on Windows Vista and updates the manual to match 

Release 8.3.6 Fixes a bug in the Ten rep test where the first rep resistance did not increase. 


Release 8.3.5 Adds units text in places in the PC software. Restores a missing error message.


Release 8.3.4 Improves handling and positioning of multiple data windows on the PC software.  Pressure processor software is updated to correct an incorrect operating mode of one of the chips in the processor box.  No errors due to this bug have been noted, however it is corrected.  Chip system portion of the software is updated to deal with the new time keys.  This part only affects those customers who have both A420 and Power chip system machines.  A420 does not use the time keys.


Release 8.3.2 Adds software to reduce valve sticking. Adds software to diagnose valve problems. Adds a software lockout to prevent the subject from clearing data less than 10 seconds after a rep is completed. 


Release 8.3.0 Adds diagnostics that help in troubleshooting a machine with a problem in the valve assembly.  Adds Drag and drop, an A420 data file can be dragged from Windows Explorer and dropped onto our application and opened.  Adds a timeout to prevent a subject from clearing data with the thumb buttons until the exercise arm has been still for 10 seconds.  Adds code to prevent multiple copies of the A420 application from opening at the same time.  The manual is updated.  The data clear timeout feature was added after the manual update and thus not included in the manual.


Release 8.2.5 Fixes a hardware problem that causes the USB chip reader to not recognize certain newer data keys.  Also corrects an error in software that causes the acceleration data collected from the exercise machine to be in error or be limited in size.  If you find that you need to use acceleration data from data files collected with an older version of the software, contact Keiser.  It is possible to produce software that will correct the error in most circumstances.  If there is sufficient demand for this feature, we will make a utility to do so.


Release 8.2.4 Corrects errors in changing colors of objects on the test charts.  It was not possible to change the colors of some traces in previous versions which made them difficult to view on some monitors.  This release also corrects an "overrun error" which would occur on some slower PCs.  Reliability of data download is improved.  The PC software is more friendly to use on a machine with a restricted user account.  A bug which would cause the program to hang when a minimized windows is clicked on is fixed.  This release only changes the PC software, if you have installed 8.2.3, it will not be necessary to reflash the machines.  In all cases, the PC software will warn of out of date software on the exercise machine.  You need only reflash if this warning appears.  The manual has not been changed for this release.


Release 8.2.3 adds software to test for a memory failure that has been seen on some processor modules in exercise machines.  Software has also been improved on the PC to make the download of large datasets more reliable.  The documentation has not changed from 8.2.2.  The new test will display a dialog box that warns of the error when the PC software is first started if a connected exercise machine has the defect.   No message will appear if there is no defect.


Release 8.2.2 makes only minor changes to 8.2.0.  Documentation of the variable test chart is improved.  A small change in the way peak data are located is also made as well as minor improvements to keyboard handling in some of the screens.  If you have already installed Release 8.2.0, you will need only to run the setup file.  The software in the exercise machine is not changed from 8.2.0 in this release.


Release 8.2.0 adds a graph display relating to the use of the 6 rep and 10 rep tests.  A side effect of this software addition is that we automatically locate and display the peak and averages of velocity, force and power for each rep.   This data is used to generate the new graph only when a 6 or 10 rep test is being done.  In all other cases, the results of this data are added to the summary screen.  This feature will be useful to those who in the past had to manually scroll through the detailed graph data to find peaks.  This release also adds software that does a better job of detecting faults in loading the software from the PC into the exercise machine.  It will be necessary to re-flash the software in exercise machines attached to the PC to take advantage of this feature.


Release 8.1.1 makes a small change to 8.1.0 to repair a bug that would cause data to be lost if a key was inserted just before an internal timer overflows from the largest number it can hold to zero.  This event used to occur 124 days 6 hours 39 minutes and 58 seconds after the machine was plugged into the wall power.  The event will still occur, however will only occur about 12 hours after a key has been removed.  This eliminates the possibility of loosing data to this rare but very real event.

Release 8.1 includes multiple bug fixes. 
Most of these are related to compatibility with Windows XP. 

On Feb 6, 2006 Release 7.8 is patched to 7.8.4.  This patch addresses the following issues:
Screen formatting is altered to accommodate long file names without overwriting important data on the screen Updated chip system drivers are included.  Previous chip system drivers would hang when importing chip data in certain circumstances.  This issue will only affect those sharing chips with production Keiser chip / power machines.  If you have already installed Release 7.8 and ran the flash procedure on all machines it is not necessary to repeat the procedure to install this update.  If there is any question, the version numbers for the machine software files listed in the manual are correct.  Only the software that runs on the PC is updated in this patch.

On March 22, 2006 Release 7.8 is patched to 7.8.5  This patch makes a change to at the handle translation for only the model 1131 leg extension.  If you already have Release 7.8 or 7.8.4 installed, you need only run the setup file that is downloaded here to update.  This version will display corrected data for files already collected.  If you have translated to at the handle data files, it will be necessary to make those over from the original data file to see the correction.

On March 28, 2006 Release 7.8 is patched to 7.8.6.  This patch makes the same change to the model 1132 that Release 7.8.5 made for the model 1131.

On May 8, 2006 Release 7.8 is patched to 7.8.7.  This patch corrects another small misprint related to embedded fonts not printing correctly in the manual and updated the display module to automatically disable the thumb button test mode.  Previous versions required the machine to be powered down to exit the thumb button test.  This is primarily a cosmetic fix and has little operational affect on the machine.

Release 8.1.0 posted on this web site in November 2006.  This release has been optimized to operate with Windows XP and Windows 2000.  Many small bug fixes are included.  This release like all others is fully compatible with data collected by previous releases.

If you are updating from any version earlier than 7.8, follow the instructions for updating in the manual which will install with the rest of the software.
The version of the manual included describes changes relevant to this release.
DO NOT mix software parts from different versions. 
If you upgrade the software on the PC, you must upgrade all the machines connected to that PC before they can be used.  You must reflash all the embedded modules on every attached machine to use this update.

The latest versions will always be able to read data files saved by an earlier release, and will correct most errors caused by defects in that earlier release. The newest versions will work on all older machines, however, older versions will not work on the latest machines. Never install a version older than that which was shipped with your hardware.