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CED M2 - PC Connectivity Problems/Multiple Objects Through Screens
Issues with PC connectivity and Windows 7, 8 or 10 has been addressed with revised firmware from CED. The revision also helps eliminate errors with sabots, shotgun wads and colored arrow shafts or fletching. CPU's with the revised firmware will no longer read full auto fire to 650 rpm. Firmware version 4.2 or newer resolved the connectivity issue. To determine the version of firmware in your M2 CPU hold down the Alt key then press the PF key. The firmware version will display momentarily at the upper right of the screen. CPU's must be returned to CED to be updated.

The CED M2 uses generic drivers bundled with Windows. If you are notified that the driver did not install correctly when you first plug in the CPU, open the device manager and look under USB devices with a yellow question mark icon. Right click the icon and delete the driver. Unplug the CPU from your USB port, then reconnect to force install the Microsoft driver.

Windows Software

link markCED M2 (USB) Data Collector v. 3.6.2
- (Released 11/4/12) Download utility for the USB M2 model and XP-SP3 through Windows 10 (not Win98 or ME). This file is required to download data directly into the RSI Shooting Lab. Shooting Lab owners should upgrade to version 4+ to use this file. Version 3.6 includes both the traditional "N-1" and "N" methods for calculating S.D. For Windows versions newer than Vista you may need to set the program compatibility mode.

link markCED Millennium Data Collector v. 2.5 - (Released 10/12/06) Download utility for the old serial Millennium model. Dated but still works on old systems with serial ports.


link mark CED M2 Manual - A close copy of the printed manual that comes with the CED M2 Chronograph, but as an Adobe Acrobat pdf file.

link mark CED Millennium Manual - A close copy of the printed manual that comes with the CED Millennium Chronograph, but as an Adobe Acrobat pdf file.

Common Causes of Light Trap Chronograph Problems

1) Too Close to First Sensor - Both visible light and heat exits the muzzle of a rifle with the bullet. If the first chronograph sensor is flooded with a flash of light or heat "plume" the velocity readings may be incorrect, produce an error or no reading at all. A minimum distance of 7 ft should be maintained between the muzzle of a large bore rifle and the first sensor. (10 ft. from the muzzle to center of the sensor bracket is industry standard.)

2) Light Conditions

Low Light - If used in low light and not equipped with the IR option, look on the ground to see if you are casting a shadow. If there are no shadows on the ground there may not be a bullet shadow for the chronograph to detect. If shadows are faint and the sky is light colored, removing the screen tops will often allow the chronograph to work. You must always shoot parallel with the sensor bracket but when shooting north/south with the sun low on the horizon, rotate the tripod head and sensors toward the sun. The CED IR option will eliminate these problems.

Lens Glare - The CED tops and support legs are wider than other chronographs but it is still possible at certain latitudes, direction of fire or time of the year for sun to shine directly into the sensor slots. This can cause "lens flare" and prevent it from reading. If this happens you can often eliminate the problem by tipping the tripod head, changing direction of fire or taping cardboard to the screen assembly to block light from entering the sensor slots.

Low Sun Angle - The CED support legs are wider and opaque to help prevent velocity "drift" with sun angle. If the sun is low on the horizon and you are shooting north or south there may be insufficient light entering the tops. Bend down and look at the underside of the tops. It should be obvious if insufficient light is entering through the tops. Tip the tripod head toward the sun to allow more light to enter the sensors. The CED IR option will also eliminate this problem.

Ground Reflection - If the screens are over bright white new concrete or snow, cover the ground with something dark or kick back the snow. A plastic trash bag works well for this purpose. Ground reflection can illuminate the under side of bullets as they pass over the sensors so there is insufficient shadow contrast for the chronograph to work properly.

3) Sensors Not Held Stable

Rail Is Mounted Incorrectly - For CED's verify your rail is mounted so the front screen cannot swing upward. The hinged portion of the rail should be between the tripod head and the furthest sensor. If the first sensor lifts with each shot the distance between the screens is reduced and a slightly higher velocity will be detected.

Poor Tripod - The support legs and tops can move from muzzle blast, but the sensors MUST be held stationary. If you are getting readings drastically lower or higher than what you know the round is shooting it is because the tripod is not holding the sensors still. This problem can be eliminated by mounting the screens on a better tripod or weighting each end of the rail with a sand bag.


Other Questions Pertaining to Optical Chronographs

Why won't optical chronographs work on a cloudy day or under shade?

All chronographs using conventional skyscreen technology need light. The chronograph measures velocity by sensing a bullet's shadow as it passes over each sensor. Most problems with conventional skyscreen chronographs, of all brands, relate to lighting conditions. In short, if you cannot see your shadow on the ground there may be no bullet shadow for the chronograph to see. This is why most offer artificial lighting upgrades. On days where there is a solid white cloud cover but enough light to produce shadows you can often get the chronograph to work by removing the top diffuser.

How can I test an optical chronograph without shooting through it?

Test the chronograph indoors in low light on a table or counter top as follows. Locate the sensors as close to each other as possible. Do not attach the screen tops so you can pass a light over the top of the sensors.

Focus a small bright flashlight (like a Mini-MagLite™) to a fine beam. and pass the light beam across the top of the sensors from the start to stop sensor with a quick wrist "flick". You should be able to artificially create velocity readings to verify the sensors and CPU are working. It may take a few trys to develop the right technique.

Do not be concerned if a CED display reads "error". An "error" is indicated for any shot where the velocity is 7% off the running average. Since you are not likely to "flick" the flashlight the same every time, this is perfectly normal.

Will I get more precise readings if I use a longer mounting rail ?

In short, not if your chronograph is running a modern fast chipset. Old optical chronographs (may still work) used chips that were very slow by today's standards. A chronograph cannot be more precise than the "clicks" on it's clock. So, the time to pass from start to stop relative to chipset clock speed relates directly to precision. This is why the old chronographs had rails as long as 10 feet. Technology did not yet have sufficiently fast chips so they extended the time between start and stop with long rails. With the first generation optical chronographs, each clock "tick" equated to about 15 fps on each end of a 2 ft. rail for 3,000 fps rifle shots. That is a built-in potential error of 30 fps! When using a 10 ft. rail, this error could be reduced by a factor of 5. A serious shooter trying to load to single digit S.D. with at least 30 fps random error in each number will have obvious problems reproducing acceptable results. Reducing the error to 6fps with a 10 ft rail will make a big difference.

We tested the CED to prove this point. A chronograph was connected to sensors spaced at 6 ft. and another to sensors spaced at 2 ft. Measured velocities were virtually identical and never varied by more than a couple fps.

Chron Screen Space

The following is actual data collected using this sensor configuration. The measured velocities will never be a perfect match because velocity erodes differently over each of the two distances and the measured velocity is not at the midpoint for either set of sensors. Still the difference was extremely little (less than 1 fps or .07 percent) and way under s.d.'s for even the best loads. We conclude there is no reason to shoot over longer rails if you have a modern chronograph. Long rails only complicate setup, increase the chances of accidentally shooting part of the screens and reduces the field of fire without relocating the chronograph. This example also explains why chronographs with short distances between start and stop must have proportionately faster chip clock speeds to produce similar precision.

Test Results


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