How do I use Differential Line Drivers

[Ken W]

I'm a software geek over my head, so excuse the ignorance of my question.

I need to know what type of PXI card(s) to use to send control signals over Dual Differential Lines.

I need to replace the outputs from TI-75114 Dual Differential Line Drivers. 50-pin D-connector cables runs to TI-75115 Dual Differential Receivers at the other end, that in turn control various switches. There are 31 control wire pairs (each has a control line ZP/ZS output pins of TI-75114 and a return line YP/YS pins on TI-75114).

Old System:
TI-75114 -> 50-pin D-connector cables --------------> TI-75115 Receivers -> switches

New System:
NI-PXI chassis -> 50-pin D-connector cables -----------------> TI-75115 Receivers -> switches

Thanks,
Ken

[JoshuaP]

I think that is another term used for Differential Line Drivers is serial RS485 or RS422. If that is the case I would recommend the PXI-8431. They currently come in 2 and 4 port configurations. They have flexible baud rates so they can interface with just about every possible RS485/422 device even if you are using a non-standard baud rate. In addition, they use DMA transfers to move data and therefore do not bog the system down with interrupts. The only down side to the 843x series is that they are currently only supported on Windows 2k/XP, no LabVIEW RT support yet.

If you need LabVIEW RT support and you are going to be using a standard baud rate then you could potentially use the PXI-8421. They don't have DMA support so they use up more of the processor but they do come in a 8 port version, so you would need less of them if you are wanting to control 31 COM ports.

-Josh

[Ken W]

I ended up talking with both an NI support Engineer and a TI support Engineer to find the solution.  The NI PXI-6723 is a 32 channel AO card that will allow me to drive the differential lines at the proper levels.