Well, this was embarrassing. It turns outs that a couple a dozen or so of the first DI-155s that we shipped could not make a measurement on analog channel 1. An internal check revealed that all the DI-155s that passed calibration and were sitting in their plastic boxes waiting for labels were fine. Those in their shipping boxes with labels had the channel 1 problem. Hmmm…

It turns out that despite extensive functional tests of the DI-155 before its release, no one bothered to tell the testers that the very last step in the manufacturing process requires that a fully tested, calibrated, and functional DI-155 be connected to a PC that contains a database of all units calibrated to that point. Once connected, the serial number of the DI-155 is read, and a label spit out by a printer to be placed on the underside of the unit’s box. Its been this way with all starter kits since as long as anyone can remember. The problem is that the DI-155′s internal EEPROM is slightly more full with content because of its many ranges and other items, and one crucial location was being erased by the label generation process. You guessed it, the fully tested, calibrated, and validated calibration constants for channel 1 were being replaced with all zeros.The result was a solid, flat line zero response for channel 1 regardless of what you connect to it.

This is old news if your DI-155 has this problem. After the first several customers called with the issue it didn’t take long to discover the cause, and that same day we sent an email to all DI-155 customers informing them of the problem and a pending fix, which was released today.

So, the lesson is just when you think you’ve covered all the bases, look again. There’s probably one you missed. Our apologies to those first DI-155 customers. Your inbox should now contain an email from us describing a fix that can be downloaded from our website, installed, and used to banish this bug forever.

The data acquisition protocol document for the DI-155 is now available from our website at this link. For those not familiar with the concept of an instrument protocol, please review this link for background information.

The DI-155′s protocol is very similar to its cousin products’ protocol, the DI-145 and -149, but includes definitions that can tap the unique features of the DI-155, like programmable gain and the interpretation of its higher resolution measurements. It’s a must-have for anyone who plans to program the instrument at its native level, or from an OS other than Windows.

The Short Take

If all goes as planned we’ll ship the DI-155 data acquisition system during the week of March 12th, with assembly of the first production run scheduled to begin on Monday, March 5th. As of this moment, our online store is accepting advance orders, and shipments will occur on generally a first-ordered, first-shipped basis. If you’re in a bind because of our delays ( I know that many of you are), please tell us so in the SPECIAL INSTRUCTIONS box when you place your order, and we’ll make every effort to accommodate you.

Visit the DI-155 page and click $VIEW PRICES to order. If you’re a frequent visitor you may have to refresh the page to display the shopping cart.

Please note that specifications have evolved over the last several months. You should download and review the latest DI-155 data sheet before ordering to ensure that the data acquisition performance that you expect, is what you actually get.

The Details

Thanks for bearing with us while we put the final touches on the DI-155′s release. Late in the week of February 20th we delivered all of the first production run parts to the assembly house. Since then they have been programming their pick-and-place machines for the run.

Four PCBs and associated parts were kept behind to act as first production run prototypes. They were built by hand from the same BOM we delivered to the assembly house, and then calibrated using the prototype calibration fixture. These completed models were given to various techs to perform final testing before the assembly house builds hundreds of them. We tested such items as common mode rejection, linearity, accuracy, etc.

We found that the models were functional except for some linearity issues near ± full scale caused by an inconsistency in the BOM. This problem rectified, the models performed as expected. Since we didn’t want to take advance orders without first publishing a final data sheet (complete with detailed specifications), the advance ordering process was delayed until we could resolve this and other more minor issues.

On behalf of everyone here at DATAQ Instruments, we thank you for your patience and appreciate your continued interest in our data acquisition products.