how to develop my own SCXI module?

[bluesolyg]

According to NI,SCXI is designed open specifications. I want to develop my own SCXI module and operate it by NI-DAQ functions. I have not found any resource about what data transferred from nidaq to scxi module through scxibus. So I want to know How to develop a scxi module that supports all data acquisition modes available in daq ,Lab VIEW and cvi.

[Bill B]

Hello,

Thank you for contacting National Instruments.

Developing your own SCXI module is a challenging task. Here is some information that you will find helpful in accomplishing this task:

SCXIbus System Specification

SCXI-1180/1181 User Manual

SCXI Bus Extender

We recommend that, if you are wanting to multiplex AI channels, you make your module have 8 differential AI channels and use the SCXI-1352 Cascading Cable Adapter to an NI SCXI AI module (such as the SCXI-1140, 1141/2
/3, etc.) that is capable of multiplexing through the driver. For more details see the SCXI-1352 Module-Cascading Cable Assembly Installation Guide

I hope you find this information helpful for your design.

Regards,
Bill B
Applications Engineer
National Instruments

[bluesolyg]

Hello:
Thank you for answering my question. I have looked through the information you mentioning, but it isn't exactly what I want.Maybe I don't clarify my mind.I know the scxi bus is based on SPI bus, but how does the DAQ board transmit command and data to the scxi module and how does the scxi module explain what it's receipt. For example, when I call SCXI_Reset function, the scxi module have received a series of data, how does the module set it's default state according to these data? In other words, what data does the DAQ transmit and how does the scxi module explain the data?
Thank you!
Regards

[Bill B]

Hello,

The question that you have asked is beyond the scope of support that we offer. It appears that you would like to design a multiplexed module which would require register-level programming. Our drivers do not support register level programming for SCXI modules. Therefore, we only support the development of parallel mode modules. In most cases, these modules contain eight input channels that condition each channel and then pass the signals directly to the eight channels of your DAQ board or they are cascaded to a multiplexed module such as the SCXI-1140/1/2/3. In either case, the custom module is transparent to the system.

I am very interested in the application or the specs that you desire in your custom module compared to what we curr
ently offer in our product line. Could you please tell me what you desire for specs? Also, could you please tell me if you were planning on building multiple modules or just a couple? I look forward to hearing from you.

Bill B

[bluesolyg]

Hi Bill
Most NI scxi modules can meet all our customer's demands.But in some special circumstances,they can't all reach the customer's demand.some our customers ask modules have wider range and more choices in gain or higher frequency in filtering,some ask modules had better be all programmable,they do not want to frequently insert and pull out the module for change of the parameter.
So we want develop complementary multiple modules for the customer's special demand.In this way we can get more orders for system integration.

[Bill B]

I admire your ambition to design your own modules. However, we do not support customers who are designing their own multiplexed modules. Again, a multiplexed module will require register-level programming which we do not support. If you want to design your own modules, I encourage you to design an eight channel parallel mode module which you can cascade to one our multiplexed modules such as the SCXI-1140. Please see this tutorial for information on cascading:
http://zone.ni.com/devzone/conceptd.nsf/webmain/9330CB13E1D6169386256B79005A842B?opendocument

Regards,
Bill B

[bluesolyg]

Thank your compliment and suggestion.But register-level programming to me is not still very clearly,is it SCXI chassis register-level programming or PCI E Series Register-Level Programming?And Is it essential to understand thoroughly DAQ-STC？


Regards,
bluesolyg

[Bill B]

Hello,

The register level programming would need to occur on both the E-Series device and your custom module. Since the E-Series board is controlling your chassis, you would need to program some registers on the E-series device to initiate communication with your custom module, then you would need to have registers on your module which would allow certain action such as selecting a particular channel or setting a specific gain. We neither support the register-level programming of the E Series board nor the register level programming of your custom module. This is why it is usually best to make an 8 channel parallel module that is transparent to the chassis, yet conditions your signals to your liking and then ca
scades them into a multiplexed module, such as the SCXI-1140, using the SCXI-1346 adapter cable.

Regards,
Bill B