- From: John Conner <conner_at_empiredi.com>
- Date: Sat, 15 Jun 2002 22:01:03 -0600
Daniel, Can't say than I've noticed problems due to signal level - unless the channels wore open in which case just about any reading is possible on an unused channel. The big problem we've seen with the DAS16JR/16 boards was due to ringing on the CTR 2 OUT line. This like drives the A/D pacer and in turn the MUX on the board. Much of the A/D control is in the XILINX FPGA . The XILINX is a very fast chip and we found on cards built in the 95-97 time frame that the MUX could be clocked by the ringing on the CTR_2_OUT line. I was told that the problem had been fixed in newer board by adding an inline resistor. My solution has been to cut the CTR_2_OUT line in the cable that connects to P1. This keeps the line from being a long transmission line. Unless you have a real need for the signal .... I think that it is pin 2 on the P1 connector but check to be sure. I don't know if this will help your problem or not. I still do not have the ISA version working. It does more or less what you describe but is not amplitude sensitive. What sampling rate are you using and do the other channels show more or less the correct value for the load applied? John > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > Hi, > > We've got the following problem with our PC104das16jr/16 card. We connect= > ed a=20 > load cell to channel 14, none of the other channels are connected and the= > y`re=20 > all grounded. When we start measuring, everything seems to be fine (excep= > t=20 > from the fact that the signal we get varies pretty much..we expected it t= > o be=20 > steady), but when we start increasing the weight on the load cell the sig= > nal=20 > starts scattering on channel 15 and 16 though there is nothing connected.= > The=20 > more weight we put on the load cell, the more channels get involved... I=20 > guess it`s a problem with the MUX counter on our card, but I'm not sure h= > ow=20 > to handle this...I once read here that one fast solution would be to cut = > the=20 > cables, but this is not a solution for us since we need the full length o= > f=20 > our cables. Did anyone encounter the same problems ? =20 > > John, I've read your mail concerning your DAS-16 card on comedi, probably= > you=20 > can help us here ? > - --=20 > - ---------------------------------------------------------------------- > "Schlage die Trommel und f=FCrchte dich nicht" (Heinrich Heine) > > Daniel Koch (danielkoch_at_gmx.net) > -----BEGIN PGP SIGNATURE----- > Version: GnuPG v1.0.6 (GNU/Linux) > Comment: For info see http://www.gnupg.org > > iD8DBQE9C2i36i7okj1aOg0RAgiAAKC9WBniTOvHtEtgUg8MUO2NQc1MwQCeM0HG > lZesnVZIBewfauxw6Luwp/s=3D > =3DEVF3 > -----END PGP SIGNATURE----- >
Received on 2002-06-16Z03:01:03