The IOTech Micro488/P has the same basic design (microcontroller drives bus directly) and therefore should be assumed to have the same potential deficiency and costs about $500 today new from the factory (serial interface only). The only limitation they show on their web site is that it can only control up to 8 instruments, there is no mention of data rate or cable length. I have two of them and so far they control everything I have thrown at them. Being powered from the serial bus (they draw about 5mA), they don't have much pull-up capability by themselves, probably very far from the IEEE-488 spec requirements. They advertise it as being intended for laptops, but many laptop serial ports won't provide the drive power/voltage it requires...
http://www.iotech.com/catalog/ieee/mini_controller.html I would like to make sure we find out where the problem is. I agree with John that the Prologix has proven to be dependable and that the design approach was a reasonable compromise. Measurement Computing sells a GPIB driver chip that is in a small surface mount package, but it costs more than the Atmel chip Abdul is using, and it's just a driver. Didier > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Chuck Harris > Sent: Wednesday, November 28, 2007 1:12 PM > To: Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] OT: Prologix GPIB and HP3478A...The Answer! > > Hi John, > > I agree in part. > > If it is known that certain GPIB instruments are not > supportable, then it is essential to have that documented > fact easily available to the buyer. Thus far, the Prologix > website, and documentation, make no mention of any possible > limitations, or deficiencies. [For instance, it clearly > cannot support the maximum defined GPIB system, or cable lengths. > That should have been mentioned.] > > The GPIB standard is very well defined. There really is no > reason to expect that a commercially made controller wouldn't > be able to operate with any GPIB controlled instrument. The > HP87B's controller will operate any device, and I am sure > that the controllers I designed as a graduate student would as well. > > I would be angry, except that I already knew that the design > had a major short cut in it before I bought my Prologix. If > you recall, I addressed that issue many months back on this forum. > > I bought my Prologix controller based on the good reports > that all of you guys posted. And the need to control a > single device, a Tektronix 7854. It will do that, so I am satisfied. > > The "Go away kid, you bother me!" approach won't win over > many customers. > > -Chuck Harris > > John Miles wrote: > > Interesting point there. I seem to recall quite a few > pullup/pulldown > > options in the Atmel port-configuration registers; this may > just be a > > matter of selecting a mode that looks more like the resistor > > configuration Chuck mentioned. > > > > Personally, I think it's fine if you support only 99% of the GPIB > > devices out there and leave the remaining 1% to the > competition. Your > > boards have proven compatible with an incredibly-wide array of > > instruments at this point. If the 3478A problem can't be fixed in > > software, I think the best answer is, "Sorry, we don't support that > > one, here's a refund." It certainly isn't worth adding > more chips (and cost) to the board IMHO. > > > > -- john, KE5FX > > _______________________________________________ > time-nuts mailing list -- [email protected] To unsubscribe, > go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
