SCXI-1127 Module behaviour

Hi,
I'm using 4 SCXI-1127 modules in 1 wire mode. Lately, I've been experiencing problems with one of the 4 modules. When i try to read resistance of 4 individual resistors by connecting them to any of the 4 channels of modules installed in slots 1,2,and 4 of SCXI 1000 chassis, it gives me correct results. But with module in slot 3 i get two 'NaN' values either on 0 & 1 channels or 32 & 33 channels. I did troubleshooting via MAX and NI-Switch soft panel, but couldn't figure out what's wrong with it. If anybody has any suggestions please let me know. Meanwhile i'll try exchanging module in slot 3 by modules in other slots.
Thank You

Hi,
I�m experiencing a similar problem. Module in slot 1 is giving me
�NaN� values. I tried swapping modules, added and deleted them through
MAX, and rebooted the PC several times. All the modules are working
correctly, when inserted in slots 2, 3, and 4 of SCXI 1000. I don�t
understand what�s causing the module in slot 1 not to work. I tried
debugging it through soft panel too, but the problem still persists
!. Any suggestions??
Thank You
Atul

Similar Messages

Multiple scxi 1127 switches scanning, dmm 4070

Hi,
I am using 2 switches SCXI-1127 in a PXI/SCXI combination chassis. The readings are done through a dmm 4070.
I need to scan 60 thermocouple channels, i.e. 32 on the first one and 28 on the second switch. Now, I found http://zone.ni.com/devzone/cda/tut/p/id/3658 stating that a scanning multiple SCXI switches is using legacy DAQ functions in niSwitch for these specific siwtch cards (1127).
What version of niSwitch was it? Is it still true now? Why is that? Or should I use the new way using DAQmx?
thank you
alex

Hi Alex,
This is still the case with NI-Switch 3.3.1. Due to hardware limitations, scanning multiple SCXI-1127 modules is not a simple task with the NI-Switch driver. I would recommend using the DAQmx example "DAQmx Multi Switch Synch.vi" if you are performing synchronous scanning. I have taken a screen shot of the front panel of a working VI to help get you started.
In general, it is more efficient to use DAQmx when scanning multiple switches. When using NI-Switch to scan multiple switches, it is necessary to maintain a session for each switch module. When using DAQmx Switch, you need only open one task. Using DAQmx Switch increases programming efficiency, keeping your code neat and maintainable.
If you need further explanation or if you have further questions, please let me know!
Chad Erickson
Switch Product Support Engineer
NI - USA
Attachments:
synchronous scanning.JPG ‏136 KB

Low level control of SCXI 1127 relays

Hi,
How can I close or open switches HLSELECT and 1WIRE of SCXI-1127 manually? There is a VI(1WireINDEP) which uses CIN to activate these switches. This VI allows to activate HLSELECT and 1WIRE relays when the SCXI 1127/1128 is used in 1 wire mode as a 64x1 multiplexer. The 1WIRE relay will always connect to 1wirelowref signal. The HLSELECT will connect to Com0+ when H-L Channels is set to Channels 0-31 and to Com0- when H-L Channels is set to Channels 32-63.
I need to control 1WIRE relay just like this VI controls HLSELECT relay. I have attached this VI. Can you please modfiy it or write a different VI to allow controlling 1WIRE relay. I should be able to open and close these two relays (HLSELECT and 1WIRE) manually thro
ugh the VI. If this is not possible, can we modify this VI so that the 1WIRE relay will always connect to com0- signal instead of 1wirelowref signal.
Thanks
Attachments:
1wireINDEP.vi ‏48 KB

Thanks for your reply. My problem is not that simple.I am using NI-SWITCH1.6 and need to continue using it. Can't I just use this VI as sub VI and call it? Here is my problem:
I am building a system to test cables that are open at both ends. A cable can have 4, 6, 8, 10, or 20 wires in it. I wish to test the resistance of each individual wire in a cable and insulation between wires. I have four SCXI 1127 modules with SCXI -1331 in a SCXI 1000 chassis. The switches are controlled by a PCI-4060 DMM.
I have written a VI ( in Labview 6.1, NI-SWITCH 1.6, NI DMM 1.6), which configures DMM for multipoint measurement and SCXI 1127 modules in scanner mode. I connect 1_WIRE_LOW_REF of all SCXI-1331s to a common point, which connects all wires in a cab
le/s under test. So, by using SCXI in scanner mode and generating scanlist, I can measure the resistance of individual wires. I use 1127 in 64 x1 multiplexer mode. This takes care of one requirement.
Now for insulation testing, I keep all wires of cables connected to switch channels and need to connect them in combinations. I can generate the combinations and pass it in a loop to close or open switches. I need help in creating correct paths and route the measurements to DMM.
For example:
Let�s say, we have a four wire cable, I need to test the insulation between them in pairs. There are six possible combinations: 1-2, 1-3, 1-4, 2-3, 2-4, 3-4. Let�s say these wire are connected to ch0, ch32, ch1, ch33 of module 4, the VI may need to close the switches as per the paths required (attached in word document).
I just don't know how can it be done.
Attachments:
Channel_combinations.doc ‏41 KB

SCXI-1127 problems

We are using a SCXI-1127 module, a NI-1331 terminal block, and a NI-1000 chassis. I set up the chassis and module correctly and wired up for 4 wire resistance measurements. I Connected the signal to channel 0A and 0B for 4 wire measurements. When i go to test, i can't get any measurements. Under the properties for the 1127 we have it set up for 4 wire mode on channels 0-15. We tried to make a virtual channel then run the tests on that channel and can't get any resistance measurements. Any ideas what could be going on here?

Hello Leonard,
First of all I would like to make sure you are connecting your signals correctly.
In the NI Switches Help (April 2003), go to the chapter "NI Switches Help >> Device Overview >> NI SCXI-1127/1128 >> 4-Wire 16x1 Multiplexer Topology". It shows there how to connect your signals and it says "In 4-wire mode, connect your excitation or source leads to xA+ and xA- and your measurement or sensing leads to xB+ and xB-".
Question 1: Are you connecting the excitation signal to 0A+ and 0A-, and the resistance legs to 0B+ and0B-?
Question 2: Use the example program "niSwitch Making Connections on a Switch.vi" in LabVIEW that s
hips with the NI-SWITCH 2.0 (or later) driver to choose the appropriate topology and to connect CH0 to COM0. If you measure in your terminal block the pins that correspond to OUT0 and OUT2, can you see the appropriate signals?
Question 3: What device are you using to measure signals from the switch? The NI 4070 DMM? Another NI DMM? If so, connect AB0 to OUTo and AB2 to OUT2 and try to get the readings in the DMM from the backplane of the chassis (see Switches Help for more information).
Question 4: How are you creating a Virtual Channel?
Talk to you later,
Claudia Lorente
Applications Engineer
National Instruments
http://www.ni.com/ask

How can I set the gain on a SCXI-1102 module without having my computer lock-up for 3 seconds?

Forgive my insolence, but did it never occur to anyone that spinning in a hard loop while polling a status register to set a gain for 3 seconds isn�t a great idea?
I have a number of SCXI-1102 modules to set the gains on, and it takes several seconds for each. Reading the documentation on the subject indicates that the SCXI_Set_Gain call polls a status register waiting for the gain to settle before returning � and it doesn�t even yield while doing so.
Are there any other ways I can set the gain? Is there a way that doesn't poll the register that returns in a reasonable amount of time?
AFAICT, there's no good reason to only allow one module to be s
etting its gain at a time. An asynchronous call it really needed - one that makes it the API programmer's responsibility to check the status of the register, or one that spawns a thread and sleeps between polls, and signals an event or invokes a callback or some-such-thing. Or you could even just sleep for three seconds after setting all the gains, this way the delay would be 3 seconds total � not 3 seconds for each gain set.

This NI-DAQ function call directly accesses the nidaq32.dll. While the nidaq32.dll is multithread safe, it is not a multithreaded DLL. This is also described in the KnowledgeBase entry 1V9DSHDM: "Can NI-DAQ Handle Different Operations at the Same Time? Is It a Multi-threaded DLL?"
You are correct that the SCXI_Set_Gain function is not asynchronous. Thus, you do have to wait till that function returns before calling the next one. LabVIEW has found a way around this. So, you can actually use the LabVIEW functions to set the gain on these modules without having to wait as you do with SCXI_Set_Gain.
Regards,
Geneva L.
Applications Engineer
National Instruments
http://www.ni.com/ask

How can I use LabVIEW 6 on a SCXI-FRQ8 module?

Hi, here is a description of our problem. We hope that you will be able to help us.
We bought from NI, a few years ago, some SCXI-FRQ8 modules. (Those modules were made by a company called Developpement Ingenierie in France) The problem is, we can not update to the version 6 of labview since we do not have the drivers to install Labview 6. The drivers we have are for Labview 5.x and 4.x.
Furthermore, we can not update those drivers by ourselves, since we do not have acces to the diagram of these VI drivers. We tried to contact that company, but no one answers. So maybe the company does not even exists anymore.
We would like to be able to install Labview 6 on these modules and if we can
make it work, we will probably buy some new SCXI-FRQ8 modules(if we can still buy them).
Thank you

The driver for the SCXI-FRQ8 provided by DI originally did not include the block diagrams. So if you try to use them in a newer version of LabVIEW, you will receive error messages because LabVIEW needs the source code to recompile the code into the newer LabVIEW format.
National Instruments can provide you with the code you need to use this module with LabVIEW 6. Request this code at http://www.ni.com/ask.
Raecine Meza
Applications Engineer
National Instruments

Trying to measure voltage through SCXI-1127/1331 1-wire connection

We have NI hardwares like: 1) Chasis SCXI-1000, 2) DMM PCI- 4060, 3) MUX SCXI-1127 and 4) Terminal Block SCXI-1331
We have a system with two large glass plates standing vertically and placed parallel to each other each having 24 electrodes on them. Distance between them is 4-5 inches. The plates are places in such a way that the electrodes are on the outer side and accessible to the user. We are trying to flow different liquids of different density through the channel in between. Please find attached a picture of it.
So a total of 48 electrodes and hence, wires are connected, 24 on both sides. On each side there are 3 rows with 8 electrodes/row, making a total of 24 wires. Wire#1-24 are on side A (say) and wire# 25-48 are on side B (the other side). The medium between the two sides will be salted water (say for now).
We want to measure potential/voltage in such a manner so that we can calculate the voltage difference between all possible electrode combinations between side A and side B. Like V1-25, V1-26, V1-27,...,V1-48,V2-25,V2-26,........,V24-48, all 24 X 24 possible combinations. We are connecting two end of a power source to side A and side B so that there is some current flowing in the water.
I have connected wire# 1-48 to 1-48 in SCXI 1331 (left out the zero to avoid confusion). Now that I'm measuring values through the program attached ("Scanning_....vi"), I can see that the first 16 values are showing some values of standards E-2. But from 17-48 are showing values of standard 5E-3 and I guess they are not taking any values at all. Can you tell me why this might be happenning?
Can 1-wire measurement be applied for this scenario. If not then let me know how to achieve our goal. I can manually take a Multimeter and measure all the combinations one by one, but measuring all the values at the same instance would be better and that only can be done by automation and I hope that the NI hardwares I have, should be sufficient to do that. Please let me know if it is otherwise.
Another thing, in one of my previous contact with NI someone mentioned connecting 1_WIRE_LO_REF. Is it needed in this case? If yes, then if I connect one end to 1_WIRE_LO_REF, where should I put the other end?
In case the program is wrong or more than 16 values can not be taken please let me know alternate path or show me how to make changes in the program. I would appreciate your help in this issue. Thank you.
Message Edited by ERT_LSU on 09-17-2007 12:16 PM
Attachments:
Scanning_of_SCXI-1127_48_write.vi ‏144 KB
IM0000021.jpg ‏767 KB
IM0000041.jpg ‏722 KB

I connected the COM of my power source to the 1_WIRE_LO_REF. There are 4-5 points to connect. I choose the middle slot. Is there any significance of assigning so many slots to 1_WIRE_LO_REF?
No change in result. Can you please test run the program I attached and see whether it's correct or not. You'll see 48 segments getting the output. First 16 of them are showing some seemingly proper values. rset are either too small or as big as 5 V.
I'm providing 5Vs from the power source. You might have seen the old analog ones. I'm using one of them. there are different Voltgae option. I'm using the 5V and so I've connected a wire from the 5V connection to one of the electrodes on B side (28th electrode) and the COM ports goes to the A side (4th electrode) and also to 1_WIRE_LO_REF.
Now I'm thinking if the program if not working. Because it seems that we are getting (seemingly) proper values for the first sixteen and something's messing up the values for the the rest of the electrodes.
Do I have to use two 24X1 MUXs i.e, use physically different boards and also two different programs to measure them? Or I can just use 1-24 as 24X1 and 25-48 as another 24X1 in the same board and measure them through the same program? Thanks in advance.
Message Edited by ERT_LSU on 09-17-2007 04:00 PM

Trying to measure voltage through SCXI-1127/1331 2-wire connection [ Edited ]

Hai ,
     this is madhava from LSU,I am working on ERT with NI hardwares like 1)chasis 1000 2) DMM PCI-4060 3) SCXI -1331(2 in number)
I have a system with two large glass plates standing vertically and placed parallel to the user.I am trying to flow different liquids of density through the channel in between.Please see a attached picture of it.
    There are total of 48 electrodes 24 on each side to which wires are connected. On each side there are 3 rows with 8 electrodes/row, say 1-24 on side A and 24-48 on side B. The medium between the two sides is salt water.
     I want to measure the potential in such a manner that I can calculate the voltage difference between all possible electrode combinations between side A and side B.I have connected a two end power source to side A and side B, i.e. +ve to side A and -Ve to side B , so   the electrode on the A side acts as the "source" and the electrode on the B side acts as "sink".
    I want to use 2 SCXI- 1331 's for this experiment.
    I tried it with 1 SCXI - 1331, but did not get proper values.So what do you suggest shall I continue this with the 1 wire or could you please help me with the two wire experiment, so that I can get more combinations.
           I hope you respond soon and in the affirmative.
With regards
Madhava
Attachments:
Scanning_of_SCXI-1331_48_write.vi ‏144 KB

Welcome to the discussion forums, Madhava!
The optimal solution is to have a 2x48 (or more) matrix so
that you could easily choose one point on either plate (column) connected to
one lead of the DMM (row0) and another point on the other DMM lead (row1).
Since the SCXI-1127 doesn’t support this configuration, you’ll have to try
something else with your existing hardware.
Because you can only use a multiplexer setup instead of a
matrix for your number of signals, the closest you can get to the above
suggestion is to measure one electrode to ground and then read the next
electrode to ground and include logic to find the difference between the two voltages.
I suggest you start with a LabVIEW shipping example (Help » Find Examples) such as niSwitch
DMM Switch Synchronous Scanning.vi or niSwitch
DMM Switch Handshaking.vi (found under Hardware
Input and Output » Modular Instruments » NI-SWITCH). You will have to modify
it to include another SCXI-1127 and set them both up in a 1-wire 64x1 multiplexer
topology. Take measurements as quickly to each other as possible on both
switches. Again, this is a workaround to what you really should be doing for
optimal performance (and the easiest setup).
The last option is to limit your measurements to electrodes
directly across from each other (or any other fixed mapping setup) and use a
2-wire 32x1 multiplexer topology. By nature, this is taking a differential
signal measurement between two constant points. This would allow you to easily
use LabVIEW’s shipping examples without modification.
I hope this helps you get a feel for your options and the
consequences of each.
Mark E.
Precision DC Product Support Engineer
National Instruments
Digital Multimeters (DMMs) and LCR Meters
Programmable Power Supplies and Source Measure Units

Verify SCXI chassis: Configuration specifies a SCXI -1600 module but nothing was detected

Hello NI Engineer,
I am using SCXI 1001 chassis with SCXI 1600 control module, SCXI 1520 signal conditioning module and SCXI 1314 connector block to acquire data from strain gage. Once I right clicked SCXI 1001 under device and Interfaces in MAX>> test>>I found a pop up window as “Verify SCXI chassis: Configuration specifies a SCXI -1600 module but nothing was detected”.
This is what I did. I connected wires from strain gage to SCXI 1314 connector block which is then connected to SCXI 1520, placed in chassis. I connected SCXI 1600 controller module to computer using a USB 2.0 cable. As soon as I switched on chassis, I found a pop up at task bar as “SCXI 1600 is detected”. I opened MAX and right clicked NI SCXI -1001 under devices and interfaces>> Properties>>selected the accessory under module tab and got “Configuration complete” message at top of pop up window, But once I right clicked NI SCXI 1001 >> test >> I found an error as mentioned above. Also once I right clicked NI SCXI 1520, under NI SCXI 1001>> Configure TEDS>> I was not able to click scan for HW TEDS option (i.e. It’s not shown up). How to overcome these two errors? Please help me. I also attached screen shots with this. I am using windows XP.
Thanks
Dhaya.
Attachments:
Error pic 1.JPG ‏115 KB
Error pic.JPG ‏97 KB

Hi Dhaya,
You seems in the correct direction to configure the SCXI hardware. There is nothing to test on the SCXI-1001 chassis instead you can test on the individual channels inside the SCXI. SCXI 1600 will auto detect the modules inside the SCXI Chassis and display it in MAX. The next step that you may need to do is to configure the Accessories (Connector Block) that is attached to the SCXI-1520 mentioned.
Once you configure the connector block, you should be able to test SCXI-1520 channel.
In regards to TEDS, Are you using SCXI-1314T connector block (http://sine.ni.com/nips/cds/view/p/lang/en/nid/13735) which is for TEDS sensors?
I hope that this helps
- Meadow -
LabVIEW 7.0 - 2011, Vision, RT, FPGA
TestStand 3.0 - 4.5

SCXI-1127 and Reset NISwitch VI

I have a question with regard to resetting the SCXI-1127 Card.
I wrote a test VI that performs the following in sequence to
verify the -1127 operation:
1) Initialize the SCXI-1127 Card
(using a Instrument Descriptor of SCXI1::5::INDEP)
2) Control a single Switch (Close ch0)
3) Close the NI Switch Reference
The switch closes correctly, because I can hear it, but here is
the kicker, if I put the entire 3 steps in a While loop controlled
by a Boolean stop switch and run the VI, the Switch chatters (its
being opened and closed continuously). Now I realize that this is
normal operation *IF* the Initialize NISwitch VI is performing a reset
of all of the switches (i.e. OPENING all switches). However, I am
setting the ResetDevi
ce Input Boolean to False when I call the
Initialize NI switch VI, but it appears that the board is resetting
anyway. Has anyone seem this before? or is the Reset Device input
on the Initialize NISwitch VI not what it appears to be to me?
(The reason I am attempting this is to assertain that I *can* call
initialize (to get a reference) without changing the current state of
the switches. this is because I am leaving the LabVIEW environment
between switch setup calls, therefore I need to close the open
Instrument reference)
Any Help would be appreciated
Rick M
Sent via Deja.com http://www.deja.com/
Before you buy.

Rick,
you are right: the reset option in this moment is not yet performing any
action inside the NI Switch driver. We apologize for the inconvenience: it
will be activated in future release of the products. Unfortunately, in this
moment it is not possible to avoid the RESET of the switch card when you
open a new session.
Maurizio
[email protected] wrote:
>I have a question with regard to resetting the SCXI-1127 Card.>I wrote a
test VI that performs the following in sequence to>verify the -1127 operation>1)
Initialize the SCXI-1127 Card>(using a Instrument Descriptor of SCXI1::5::INDEP)>>2)
Control a single Switch (Close ch0)>>3) Close the NI Switch Reference>>The
switch closes correctly, because I can hear it, but here is>the kicker, if
I put the entire 3
steps in a While loop controlled>by a Boolean stop switch
and run the VI, the Switch chatters (its>being opened and closed continuously).
Now I realize that this is>normal operation *IF* the Initialize NISwitch
VI is performing a reset>of all of the switches (i.e. OPENING all switches).
However, I am>setting the ResetDevice Input Boolean to False when I call
the>Initialize NI switch VI, but it appears that the board is resetting>anyway.
Has anyone seem this before? or is the Reset Device input>on the Initialize
NISwitch VI not what it appears to be to me?>>(The reason I am attempting
this is to assertain that I *can* call>initialize (to get a reference) without
changing the current state of>the switches. this is because I am leaving
the LabVIEW environment>between switch setup calls, therefore I need to close
the open>Instrument reference)>>Any Help would be appreciated>Rick M>>>Sent
via Deja.com http://www.deja.com/>Before you buy.

Mercury Relay Contact Resistance using SCXI 1127

I am trying to measure Resistance on PWBA with Mercury Relays using SCXI 1127, 1331 connector block and DMM 4060. I am using 2 wire mode. The Mercury Relays have 0.25 Ohm contact resistance. The readings measurements fluctuates and are high measuring from 0.7 to 1.5 ohms. I would like to know what is the contact resistance of SCXI 1127 Relays and any suggestion to improve measurements. Why the measurements fluctuates every time. Do you think any common grounding considerations or programming changes can be done to improve. Any suggetions ? Thanks.

Looks like this message is a duplicate. For those looking for the answer, please follow the other discussion thread at the link below:
http://exchange.ni.com/servlet/ProcessRequest?RHIVEID=101&RPAGEID=135&HOID=506500000008000000AF3E0000&USEARCHCONTEXT_CATEGORY_0=_200_&USEARCHCONTEXT_CATEGORY_S=0&UCATEGORY_0=_200_&UCATEGORY_S=0

2.5MHz oscillations on scxi-1127 AI channels

I'm trying to measure the circuit below through a SCXI-1127 multiplexer and I'm seeing a 2.5MHZ sinusoid when I connect my circuit output to the multiplexer. Alone, I don't see this signal, but as soon as I connect to the mux input, it pops up and it is very large. I can see this signal not only in my software but with an O'scope probe across the circuit's output. The circuit is a simple Inverting amp and I'm using LT1212 op amp. I'm also using a virtual ground between the rails since I'm running on battery. When connected to other DAQ's or Oscilloscope, I get a clean signal, but when connected to SCXI-1127, it shows up - even when the switch isn't on. Any suggestions or ideas of what the cause might be?

Classical event: Amplifier oscillate, while oscillators won't
How much bandwidht do you need?
A small cap (5-100p) in the feedback loop and a 10R right after the OP output help
The reason for the oscillation is the higher capacitive load.
Greetings from Germany
Henrik
LV since v3.1
“ground” is a convenient fantasy
'˙˙˙˙uıɐƃɐ lɐıp puɐ °06 ǝuoɥd ɹnoʎ uɹnʇ ǝsɐǝld 'ʎɹɐuıƃɐɯı sı pǝlɐıp ǝʌɐɥ noʎ ɹǝqɯnu ǝɥʇ'

SCXI--1127 relay banks layout

When using the SCXI-1127 in the 2 wire mode configuration, will it be using only the 32 relays located in the left bank of the PCB?
I am trying to measure the path resistance in this configuration, but I need to identify the relays used in this configuration. The PCB has a total of 45 relays distributed in two banks, can you confirm with me that only the 32 on the left bank are being used in the 2 wire mode configuration?

Hi maggan,
To answer this specific question and related inquiries, I strongly recommend the NI Switches Help (installed with the NI-SWITCH driver). Download the Help by itself using the following link:
NI Switches Help
http://digital.ni.com/manuals.nsf/websearch/B133DDD29F0DFCC28625746E00564E56
The relay replacement section is a great resource for information such as which relays are used to connect a particular channel to COM. In the attached picture, I've outlined the relays used to connect ch0 to com0 in the SCXI-1127's inherent 2-Wire 32x1 Multiplexer Topology.
Let me know if you have further questions!
Chad Erickson
Switch Product Support Engineer
NI - USA
Message Edited by Chad PSE on 02-17-2009 11:39 AM
Attachments:
1127 2-wire - ch0 to com0.JPG ‏121 KB

During continuous scanning thermocouples with a SCXI 1120 module is the cjc reference read each scan?

Did the developers of the DAQmx drivers improve the temperature scan capability of the SXCI 1120 module over the methods used in the traditional drivers?
When using the SCXI 1120 module for temperature measurement and in the continuous scan mode with traditional drivers the cold junction reference was only checked on the initial start of the scan. In order to maintain accuracy it was necessary to restart the scan.
For the most part I have switched to the 1125 module for thermocouple measurement but I need to use some 1120 modules on a test stand now and I will be using the DAQmx drivers on these. I was in hopes that with the DAQmx drivers this behavior was corrected.
I can conduct testing to determine this but would like to know ahead of time if this is still an issue.
Thanks

Thank you Ben for the answer.
I checked the article you referenced appears to me that I will be adding the physical address in the channel strings then do the voltage to temperature conversion and then correct the appropriate channels associated with the cjc in question. I will also need to adjust some on board jumpers for the SCXI 1120. If I am wrong please correct me.
If scanning the physical channel is possible as suggested in this article, would it not be possible to create the channel as a virtual global channel and reference it as the cold junction in Max? Then the temperature adjustment could be done at this level of acquisition rather than having to sort this out in the LabVIEW program. This takes me back to the days with LabVIEW 4.0 before we had the virtual channels and when we had to handle the temperature conversions and other scaling ourselves. Again if I am incorrect please let me know, for I would like to use the method recommended in the article if I don't have to perform all the calculations in the application.
Just wondering if anybody reading this has actually used this method. If so, how did it work for you?
I may end up building a start up routine testing for 1120 modules being used for thermocouple measurement then if found run a stop and restart scan every 5 minutes to prevent large errors from being introduced.

Connection of the pressure transmitter to the scxi-1102 module

Dear sir,
we have a differential pressure transmitter whose specifications are as follows:
Excitation:24 Vdc, output:4-20mA.(make: Cole-parmer instrumentation company)
now, we have a NI scxi-1102 and scxi-1520 module with corresponding terminal blocks.
Our question is how to connect this transmitter to the module and to which module? can we connect it to the scxi-1102? And for the excitation what we should do? please explain the detailed procedure for that.
As the excitation is 24 Vdc, i think we have to use 1102 and has to be excited externally.
Since, i m a mechanical engineer and don't have much knowledge of electronics, please explain all the details as simply as possible.
regards...
Lalit.

I am assuming a couple of things here. They are:
The input you are looking at is a slow responding signal ie less than 2 hz. The 1102 has a built in 2 hz filter.
and or the transducer you are connecting to has a slow update rate.
You are using scxi 1300, 1303, or 1308 terminal block to connect to your chassis.
Channel 0 isn't being used.
That being said, in Max, set the gain to 1
input mode to differential
You can do the scaling in Max if you want to.That's what I typically do.
Linear scAle, 1 volt = 4 ma and 5 volt = 20 ma
On your terminal block, connect a 250 ohm precision resistor across Ch 0 in ( pin 96 & 64)
In series with your current loop ( cut the wire of the existing loop)
Connect one end to pin 96 and the other to pin 64.
Put a voltmeter across the input. red lead to 96, black lead to 64
If the reading is negative flip flop the wires. If positive, good guess.
you should be ready to rock and roll.
GB
Greg Bush CLAD

SCXI-1127 Module behaviour

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