Hello Folks,

My companany are considering buying a ZonicBook/618E, however there are a few comments regards the trigger that are worrying us a bit.

Does anyone have an answer to the issue with the Tacho Channels not working well with Bently KeyPhasor outputs? We have an ADRE 408, but we quite often need more than one, and the Zonic looks like a good alternative. I've seen a few comments about using signal conditioners, any one used one and can they recommend anything?

Cheers John

I recommend doing a search on past posts regarding the Zonicbook. My understanding is that for using a prox-probe Keyphasor, you need to use one of the analog inputs on the 618. If you are using a TTL based tachometer, you can use one of the Tach input channels.

It boils down to how many channels you need and how much hardware you have. Our plant has a 24 channel setup, but it can be used in 8 or 16 channels as well.

John, I'd be interested in knowing what issues you are having with the 408. I can also likely provide some help in that I regularly used the 408 while I was with GE/Bently.

Hi John,

our 408 is a good instrument, but as I work for a consultancy company we sometimes find ourselves needing to hire equipment in to cover work, so we were in the market for an extra Multi channel box.

Following discussions with NI we are going for the I-Otech 672U 20 - channel analyzer. It's a 24 Bit box that uses the same software as the 618E. Like the Zonic it needs to use one of it's analysis channels as a Tacho input on a Bently panel, which is much less of a drawback than it was on a 16 ch Zonic set up. It looks pretty good - nice and portable which is handy for us as we fly offshore in helicopters to work on oil rigs. Copes with PAnel readings, and drives ICP kit without needing other cards.

The typical reason for issues with the "Tacho input on a Bently panel" is failure to take into account that the buffered front panel output often has a substantial DC offset voltage. If you are using a "typical" Keyphasor installation of a proximity probe observing a notch then there will be a DC voltage of approximately -9 vDC present. When the notch passes the probe this voltage will go more negative to approximately -16 to -18 vDC. Depending on the measuring device this high level negative voltage can be an issue. Why this should occur is beyond me since this is the manner in which a once-per-turn reference is acquired on virtually all machines. The 408 readily handles this as long as the Keyphasor is set up properly within the drop down menus.

Good advice John - thanks for that!

NI IOtech 672U is an great instrument. I have one and use it for collecting data for MEScope through Analyst and for monitoring through Tomas. I might warn you that when using Tomas for longer monitoring periods the system (PC and 672) sometimes locks up due to a memory error. I use the Panasonic Toughbook CF-29 or CF-30 normally for data acquisition. I just got the new Dell XFR 6400 and have not had a chance to use it yet. I am not sure if it is a PC issue or a problem with noise in the USB. I have never had a problem with the 618E's. If you are going to use it for short test runs or special testing it is hard to beat.

For the tachometer, using a dynamic channel works very well. The best part about that is you can look at the time waveform and adjust your channel settings to get the best results. You cannot see the signal going into the tach channels so it makes it difficult sometimes to determine the setting for the best triggering.