Choosing a good test-development PC

[Dynamik]

Greetings,

      We're trying to decide on a good long-term auto-test development platform which will see many LabVIEW/NI-DAQ projects, yet I've discovered I'm seriously "PCI-challenged".  We were about to spec a box with 4 PCI 32bit slots, and two PCI-E x1 slots when I found  a test using a Quad GHz ethernet card that required the PCI-X slot.

PCI-X is supposed to be backward compatable, with 3.3V PCI 1.0/2.0 - so maybe a PCI-X slot handles the "lion's share" of legacy 32 and 64bit PCI(?)  But NI DIO and the multifunction boards always have a 5V line - does that mean PCI-X is no-good for NI-DAQ boards?

I don't know of any DAQ products using PCI-E, but another developer wants the x1 bus.  Should we expect to see PCI-E devices, and do PCI-E x1 devices work in x16 slots? (that way we could accommodate more possibilities with a single slot.)

I know one-size will not fit all future tests, but what's your sense of a flexible PCI-slot configuration.

Many thanks for any advise.

[Collin M]

I'll answer your specific questions first:
 

PCI-X is supposed to be backward compatable, with 3.3V PCI 1.0/2.0 - so maybe a PCI-X slot handles the "lion's share" of legacy 32 and 64bit PCI(?) 

PCI-X is compatible with PCI. You can plug a 32-bit PCI card into a PCI-X slot and it will work. You can even plug a 64-bit PCI-X card into a 32-bit PCI slot and it will also work, although it won't have as much bandwidth as plugging into a 64-bit slot. You mentioned you had a 4-port ethernet PCI-X card. You should be able to plug this card into a 32-bit PCI slot although it may be bandwidth limited. Do you know what the necessary throughput is for this card? If it does not do require high throughput then plugging it in to a 32-bit PCI slot might work.


But NI DIO and the multifunction boards always have a 5V line - does that mean PCI-X is no-good for NI-DAQ boards?

5V only PCI signaling is no longer supported by the latest PCI spec. This applies only to the signaling level and not power delivery. There is a separtate power rail for the voltage used by the PCI transceivers. The latest spec removes support for devices that can only use 5V PCI signaling. Devices that only use 3.3V and devices that use 3.3V or 5V (universal signaling) are still supported. The 5V on the connector of a DAQ card has nothing to do with the 5V that can be used for the PCI signaling level. Any NI-DAQ board that supports universal signaling should work in a PCI-X slot. You can recognize a PCI card that uses universal signaling by the number of notches in the PCI connector. Cards with universal signaling have two notches. Cards with 5V only PCI signaling have just one notch. Cards with 3.3V signaling also have only one notch but I don't think NI makes any 3.3V only cards.

I don't know of any DAQ products using PCI-E, but another developer wants the x1 bus. 

NI does have some PCIe DAQ products. Go to ni.com, select products, then DAQ. You will see the DAQ products available. NI also has PCIe-based GPIB and Image Acquistion products.

Should we expect to see PCI-E devices, and do PCI-E x1 devices work in x16 slots? (that way we could accommodate more possibilities with a single slot.)

Any smaller sized PCIe card is required to work in a larger sized PCIe slot, but only as a x1. This means that a x1 PCIe card will work in any PCIe slot, including a x16 slot. A x4 PCIe card will work in any slot larger than or equal to x4. If the slot is larger than x4 the card may only function as a x1 card, meaning the bandwidth will be limited.



I know one-size will not fit all future tests, but what's your sense of a flexible PCI-slot configuration.

You need to consider bandwidth requirements in addition to the number of slots. PCI-X support will dicatate the type of system you must use. If PCI bandwidth is not sufficient for the software that uses the PCI-X card you must buy a system with a PCI-X slot. Typically these are server or workstation class systems as opposed to desktop system. It may be possible to work around this by using multiple ethernet cards.

Message Edited by Support on 03-06-2006 08:44 AM

[Dynamik]

Hi Collin,

First, huge Thanks for this help!!!.

I'm drawing from your post that most [new] NI-DAQ PCI products support universal signaling - and should work in 64-bit PCI-X slots (whether @100MHz or @133Mhz).  Also. while PCI-E x16 slots accommodate all [x1 through x16] PCI-E products, the x4 (x8?) cards my be constrained to x1 speeds.

It sounds like (if it exists) a MB with 4 64bit PCI-X (2 @100Mhz, 2 @133MHz) and two PCI-E x16 slots will give pretty good coverage for both NI and non-NI PCI hardware.

BTW, the "Intel PRO/1000 MT Quad" PCI=X 64bit Ethernet adapter is keyed to Not fit 32bit PCI!

Cheers.

[Collin M]

>>I'm drawing from your post that most [new] NI-DAQ PCI products support universal signaling - and should work in 64-bit PCI-X slots (whether @100MHz or @133Mhz). 

Yes, I should have made that clearer. Most new NI PCI cards are keyed for universal PCI signaling and will work in any PCI or PCI-X slot. Note that I said "most" and not "all". Also, if you plug a normal 32-bit/33MHz PCI card into a PCI-X slot, all the PCI-X slots on that physical bus segment will be limited to 33MHz. So if you plug a PCI DAQ card and your Intel PRO/1000 MT Quad card into two PCI-X slots on the same physical bus, the Intel card will only run at 33MHz, not the 100MHz or 133MHz at which it could run.


>> Also. while PCI-E x16 slots accommodate all [x1 through x16] PCI-E products, the x4 (x8?) cards my be constrained to x1 speeds.

Yes, it is typical that any non-graphics card plugged in to a x16 slot will function at x1 speeds. The reason for this is that graphics cards are typically output type cards, meaning that the typical throughput out of the card to a device (ie, a monitor) is much greater than the throughput in to the card from a device. This is obviously true for a graphics card where almost all of the throughput is from the card to the monitor. As a result of this mismatch in throughput direction, some silicon vendors have made some optimizations that allow graphics cards to work just fine at x16 throughput levels, but other input-type cards will not have that throughput for the input direction.


>>It sounds like (if it exists) a MB with 4 64bit PCI-X (2 @100Mhz, 2 @133MHz) and two PCI-E x16 slots will give pretty good coverage for both NI and non-NI PCI hardware.

Remember that a physical PCI bus will be limited by the slowest card installed. If a 33MHz PCI card and a 100MHz PCI-X card are plugged into slots on the same physical bus, the PCI-X card will only operate at 33MHz. Also, I'm not aware of any systems yet with two x16 PCIe slots but I may be wrong. The number of applications that can make use of bandwidth greater than what is provided by a x4 connection is small. The silicon required to implement a x16 slot is relatively large.


>>BTW, the "Intel PRO/1000 MT Quad" PCI=X 64bit Ethernet adapter is keyed to Not fit 32bit PCI!

Remember, cards are keyed for PCI signaling voltage levels not bus width. If the Intel card doesn't fit in a PCI slot, it must be that the PCI slot is 5V and the card is 3.3V only.

[Dynamik]

> Remember that a physical PCI bus will be limited by the slowest card installed.

Good point - Thanks!

If an MB supports both PCI-X 100MHz and 133MHz busses, perhaps we'll have some flexibility there.  For instance, if we have need for PCI-X 133MHz speed, then (i think) 33MHz PCI cards would be safe in the PCI-X 100MHz slots. (?)

Cheers.

[Collin M]

I think that a 133MHz PCI-X bus can have only 1 load (not 100% sure about that). The important thing to remember is that a particular physical PCI-X bus will function at the clock rate of the slowest card on that physical bus. Systems usually provide documentation about the configuration of the PCI/PCI-X busses.

If you need a particular PCI-X card to run at 133MHz I don't think there can be any other cards on that physical bus segment.