after finishing designing my DAQ system , only 2 from 4 scxi modules can give readings !!!!

[daq problem]

after finishing the connections of DAQ system ( for monitoring and datalogging for 90 variables ) which
consist of:
-(4)scxi1100 32 channels -multiplexer- amplifier (installed in slots 2,5,8,11 of the chassis)
- PCI6023 card
- scxi 1001 chassis with 12 slots
- (4) scxi-1308 channel therminal block
- labviwe base package for window
- most of the signals come in mA _0-5mA, some come
in Volts (0-1 volt) and (0-5volt)

my problem is: i could read only the signals from the 1st (in slot 2) and the 4th(in slot 11), and no reading from the other 2, even with using the MAX .
i tried to connect scxi-1308 channel therminal block from scxi 1 to 2 and 3 , and i got rea
ding which means the scxis are ok , also ive checked the signal which comes to 2nd , 3rd scxis, i found there are signals at the output of 1308 channel therminal block for every one.
is something wrong with channel addressing ( SCXI channel syntax)
i hope some one can help me
thanks in advance

[Bill B]

Hello,

Thank you for contacting National Instruments.

The first thing that should be noted is that the SCXI-1308 terminal block is used for current inputs. The SCXI-1308 has 249Ohm shunt resistors through which your input current is passed to produce a voltage. This voltage is then measured by the SCXI-1100. This means that you should be able to measure your current signals, but in order to effectively measure your voltages, you will need to remove the shunt resistors for each voltage input channel you have connected to your SCXI-1308.

The next thing that should be noted is that the SCXI-1100 is a jumper programmable module. This means you have to set jumpers inside the SCXI-1100 module and then make sure that the jumper settings match the configuration settings in MAX. Here is a link to the SCXI-1100 User Manual if you need information on how to set the jumper properly:

http://digital.ni.com/manuals.nsf/websearch/0790D3C92CF4B16E8625665E00712865?OpenDocument&node=132100_US

If you are using the SCXI channel string to address individual channels, you will need to make sure you use the following string: scX:mdY:Z where X is the chassis number (ie. 1), Y (ie. 2, 5, 8, 11) is the module number, and Z is the channel number (ie. 0, 11, 19, 31)

Also, if you have other modules in your system, you will want to make sure that you have your PCI-6023 cabled to the correct module. Please see page 10 of the SCXI Quick Start Guide to ensure that you are connected to the correct master module:

http://digital.ni.com/manuals.nsf/websearch/7974503CC2946D0886256E6300748710?OpenDocument&node=132100_US

I recommend that you that you delete your chassis configuration from MAX, verify the jumper settings in each SCXI-1100, make sure that you are cabled to the correct master module in the SCXI-1001 chassis and also make sure that you have removed the 249Ohm shunt resistors from the channels of the SCXI-1308 to which you have voltage signals connected.

Regards,
Bill B
Applications Engineer
National Instruments

[Bill B]

Hello again,

I noticed I made an error when stating the SCXI channel string. It should be shown as: scX!mdY!Z

Sorry for the mistake.

Bill

[daq problem]

Hi Bill, Thanks for the response

I made new configuration(as you recommend me) and it works, when using MAX , all signals are ok, but when using labview the reading weren't ok,it seems that the labview neglect the scaling , i'll explain how: if i measure current of 1.0mA by x channel with scale (temp) which convert every 1mA to 20 degree (0-5mA) gives (0-100degree), when i checked the channel by MAX i got reading of 20 , but with labview i got 0.249 which means ( my thought) that its measurment of the volts reading across the resistor 249 Ohm

i tried to use the syntax string scX!mdY!Z but without any use , can any one guide me to any same example code, to check my system

thanks in advance

byeee