How to Use Two SCB-68As & a PCI-6259 to process more than 16 Differential Inputs

[Bobity1]

I've got  Two SCB-68As & a PCI-6259 connected to my Windows 7 32 Bit PC running Matlab R2014a.

If I try and run the following Matlab script :

s= daq.createSession('ni');

ch1 = addAnalogOutputChannel(s,'dev1', 'ao0', 'Voltage');

ch2 = addAnalogOutputChannel(s,'dev1', 'ao1', 'Voltage');

ch3 = addAnalogOutputChannel(s,'dev1', 'ao2', 'Voltage');

ch4 = addAnalogOutputChannel(s,'dev1', 'ao3', 'Voltage');

in1 = addAnalogInputChannel(s,'dev1', 'ai0', 'Voltage');

in1.InputType='Differential'

in2 = addAnalogInputChannel(s,'dev1', 'ai1', 'Voltage');

in2.InputType='Differential'

in3 = addAnalogInputChannel(s,'dev1', 'ai2', 'Voltage');

in3.InputType='Differential'

in4 = addAnalogInputChannel(s,'dev1', 'ai3', 'Voltage');

in4.InputType='Differential'

in5 = addAnalogInputChannel(s,'dev1', 'ai4', 'Voltage');

in5.InputType='Differential'

in6 = addAnalogInputChannel(s,'dev1', 'ai5', 'Voltage');

in6.InputType='Differential'

in7 = addAnalogInputChannel(s,'dev1', 'ai6', 'Voltage');

in7.InputType='Differential'

in8 = addAnalogInputChannel(s,'dev1', 'ai7', 'Voltage');

in8.InputType='Differential'

in9 = addAnalogInputChannel(s,'dev1', 'ai8', 'Voltage');

in9.InputType='Differential'

in10 = addAnalogInputChannel(s,'dev1', 'ai9', 'Voltage');

in10.InputType='Differential'

in11 = addAnalogInputChannel(s,'dev1', 'ai10', 'Voltage');

in11.InputType='Differential'

in12 = addAnalogInputChannel(s,'dev1', 'ai11', 'Voltage');

in12.InputType='Differential'

it fails on :

in9.InputType='Differential'

Is there some switch setting which I need on the second SCB-68A so that I can contiue my addAnalogInputChannels so that they are active and working as Differential InputTypes on the second SCB-68A ?

Thanks

Rob

[johnsold]

Rob,

Have you read the manual? Table 3-1 of the M Series User Manual specifies the input pairs for differential channels:

For differential measurements, AI 0 and AI 8 are the positive

and negative inputs of differential analog input channel 0.

Similarly, the following signal pairs also form differential

input channels:

<AI 1, AI 9>, <AI 2, AI 10>, <AI 3, AI 11>, <AI 4, AI 12>,

<AI 5, AI 13>, <AI 6, AI 14>, <AI 7, AI 15>,

<AI 16, AI 24>, <AI 17, AI 25>, <AI 18, AI 26>,

<AI 19, AI 27>, <AI 20, AI 28>, <AI 21, AI 29>,

<AI 22, AI 30>, <AI 23, AI 31>

Lynn