PXIe1073 with two NI-4461 cards

[dsb@NI]

The 4461 specifications indicate an internal timebase accuracy of 20 ppm. So, if you start two 4461 devices at the same time, and you set the sample rates to the same value (those rates will get resolved to exactly the same values), the relative timebase error between two devices could be as much as 2*20 ppm. Given OP is seeing ~1 ppm, it is fair to say that these clocks are accurate (within 20 ppm) and fairly well matched (within 1 ppm). But, they are not clock synchronized. 1 ppm is not big, but at 200 kS/s, 1 ppm translates to 720 samples per hour. However, channel expansion will clock synchronize and start synchronize all the channels in the task. To mcduff's question: channel expansion takes care of all routing of triggers and clocks. @Tamirsh, channel expansion results in zero drift between devices even if there is a small error in absolute clock rate per Yameada's comment.

[Henrik_Volkers]

Doug,

I tried to search LabVIEW Help (the 'modern' one .. LV 25Q1 😕 ) for 'channel expansion' but get no meaningfull result 😞

Do you have some links for concept, supported devices, .... ?

How does it relate to NI-Sync/T-Clk   and how does it work together with NI-Scope/FGEN ... ??

Edit: I found some knowledge articels in the web search ..   But shouldn't there be a hit in the LabVIEW help?

[santo_13]

---

@Henrik_Volkers wrote:

Doug,

I tried to search LabVIEW Help (the 'modern' one .. LV 25Q1 😕 ) for 'channel expansion' but get no meaningfull result 😞

Do you have some links for concept, supported devices, .... ?

How does it relate to NI-Sync/T-Clk   and how does it work together with NI-Scope/FGEN ... ??

Edit: I found some knowledge articels in the web search ..   But shouldn't there be a hit in the LabVIEW help?

---

Channel expansion is currently supported by the following drivers,

NI DC Power
NI Scope
NI Digital
NI DAQmx

These drivers under the hood uses TCLK sync and other concepts to synchronize the instruments involved in the channel expansion or multi-instrument sessions.

[mcduff]

---

@santo_13 wrote:

---

@Henrik_Volkers wrote:

Doug,

I tried to search LabVIEW Help (the 'modern' one .. LV 25Q1 😕 ) for 'channel expansion' but get no meaningfull result 😞

Do you have some links for concept, supported devices, .... ?

How does it relate to NI-Sync/T-Clk   and how does it work together with NI-Scope/FGEN ... ??

Edit: I found some knowledge articels in the web search ..   But shouldn't there be a hit in the LabVIEW help?

---

Channel expansion is currently supported by the following drivers,

NI DC Power
NI Scope
NI Digital
NI DAQmx

These drivers under the hood uses TCLK sync and other concepts to synchronize the instruments involved in the channel expansion or multi-instrument sessions.

---

I don't think Channel Expansion is supported by NI Scope; I had to use TCLK and sharing the reference clock to sync modules just recently. Not sure about the other drivers, but I thought DAQmx was the only API that supported it.

[dsb@NI]

I have only used channel expansion in the context of DAQmx devices. DSA family of devices were the first DAQmx devices to support channel expansion.

Easily Synchronize and Trigger NI-DAQmx with Channel Expansion

@tamirsh, how goes your effort?

[santo_13]

---

@mcduff wrote:

---

@santo_13 wrote:

---

@Henrik_Volkers wrote:

Doug,

I tried to search LabVIEW Help (the 'modern' one .. LV 25Q1 😕 ) for 'channel expansion' but get no meaningfull result 😞

Do you have some links for concept, supported devices, .... ?

How does it relate to NI-Sync/T-Clk   and how does it work together with NI-Scope/FGEN ... ??

Edit: I found some knowledge articels in the web search ..   But shouldn't there be a hit in the LabVIEW help?

---

Channel expansion is currently supported by the following drivers,

NI DC Power
NI Scope
NI Digital
NI DAQmx

These drivers under the hood uses TCLK sync and other concepts to synchronize the instruments involved in the channel expansion or multi-instrument sessions.

---

I don't think Channel Expansion is supported by NI Scope; I had to use TCLK and sharing the reference clock to sync modules just recently. Not sure about the other drivers, but I thought DAQmx was the only API that supported it.

---

NI Scope started supporting from 19.1, Using Multi-Device Sessions With NI-SCOPE - NI Community

Pass comma separated list of fully qualified channels to Initialize, like you would do in DAQmx.
Initialize - NI

[Henrik_Volkers]

The interesting part would be to sync different devices ...like it's mentioned for DAQmx

from santo s link: 

 Using Multi-Device Sessions With NI-SCOPE - NI Community

Hardware and Software Requirements

Hardware: Multiple PXI oscilloscopes of the same model in the same PXI chassis

Software: NI-SCOPE 19.1 or later

[dsb@NI]

---

@Henrik_Volkers wrote:

The interesting part would be to sync different devices ...

---

 Channel expansion works for different devices in the same chassis. I have synchronized many different combinations of DSA devices: 4499, 4464, 4461, 4468,  etc.

Channel expansion is not supported across different drivers - this requires explicit synchronization code and routing/connections.