Which multiplex card to get for a new Keithley DAQ6510? - Page 1
Forum section: electronics / testgear

author: Circuitous
author_rank: Unknown
timestamp: September 28, 2018, 10:22:04 pm
content: I am looking at getting a Keithley DAQ6510, but which multiplexer (scanning) card to get for it first?- Didn't want to hijackthe other DAQ6510 thread, since that's mostly about the issues around the 6510.7700 20-channel, Differential Multiplexer Module7710 20-channel Solid-state Differential MultiplexerWhat experiences do members have with the 7700 and 7710 cards?General requirements:Mostly low voltage DC and K-type temperature measurementsSome current measurements, usually mA or uASome need for curent measurements over 100mASome need for AC line measurements (120VAC)Logging over long periods, several weeksVoltage and current readings will rarely be close to max on the 7700It looks like the main differences in capabilities between the cards are:7700 has higher voltage and current on the channels7700 has max life expectancy of 10^8 cycles7710 is limited to 60V and 100mA7710 has max life expectancy of 10^10 cycles7710 can sample up to 500 channels/secondThe standard 7700 card has been around a long time and has a wider voltage and current rangeThe solid-state card is appealing due to the speed and long life.I can probably script(TSP) the logging to use a separate Keithley meter to read the occasional high voltage or high current signalsI look forward to member feedback on these cards.-- Thanks!

author: Vgkid
author_rank: Super Contributor
timestamp: September 29, 2018, 05:06:06 pm
content: The 7700 is also specified for thermocouples.Never used a scanner , so no help from me.

author: HKJ
author_rank: Super Contributor
timestamp: September 29, 2018, 07:05:34 pm
content: I would say it depends on what you need.The 60V limit on the solid state card is not only on a channel but also between channels, this means everything has to be at about the same potential.The advantage of the solid state card is the fast scanning and the much longer lifetime.With my applications I would go for the solid state card, most of my test are done at low voltage.

author: rx8pilot
author_rank: Super Contributor
timestamp: September 29, 2018, 08:04:47 pm
content: I have the 7700 in my Keithley 2700 DMM. No issues with it at all. I only use it occasionally since it only gets used on the big tests when I am nearing completion on a project. The life cycle was not much of a concern. I may have chosen the the solid state option if I found a good deal - but the 7700 gives me everything I need with a lot of room to spare in terms of reliability.Wiring up a test with 20 channels is no joke.....I ignored that reality when I got the card and quickly found out how time consuming it can be. Now that I have a basic harness - it is faster to setup a test.

author: Kleinstein
author_rank: Super Contributor
timestamp: September 29, 2018, 08:42:36 pm
content: The relays can work with higher voltage and current. So for the given occasional 120 V AC or current in the higher mA range the solid state card just did not work or could be damaged. So the relay card is the only real option. One channel might use the rear / front inputs if the DAQ6510 supports this.The disadvantage of the relays is relatively slow speed, some acoustic noise and maybe slightly more thermal EMF if really at the edge of what the DMM can do. Due to the low speed the lifetime is usually not a issue unless one is really switching often / relatively fast over a long time.I don't know the Keithley card speed, but from my experience with HP and Prema scanners the relays are not that bad even for thermocouples. It just gets bad if switching is needed more often than about every 2 or 5 seconds. This may need planing to reduce the switching frequency.

author: Circuitous
author_rank: Unknown
timestamp: October 03, 2018, 02:13:46 am
content: Thanks everyone for the feedback!Based on the comments I have decided to get the 7700 card to start with.I'll reply again when I get the DAQ6510 with a 7700 in my hands!