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How many MCC USB devices can I connect to (use) on one PC?
The answer to this question can vary, as MCC has a wide variety of USB DAQ models designed over the last 10 years, but here are some guidelines. As you connect each USB device, one-by-one, if Windows properly enumerates the device(Enumeration is the process of detecting, identifying and loading drivers for a USB device), then it can be used on the PC. So proper enumeration is a hard requirement. MCC's earlier designs were HID (Human Interface Device - similer to mouse/keyboard) devices, with the simpler/slower models (miniLAB 1008, 1208LS, 1024*, 1024*, TEMP/TC) requiring very modest USB resources, while progressively faster models(1208FS/1408FS, 1608FS, 1616FS) require more. For the low end, 7 or more units can be connected. MCC specs states that two 1208FS/1408FS can be used per USB root controller, though 3 is more common. Two is a hard limit for the 1608FS, and 1 for the 1616FS ... again, these are per USB root controller. The 1616FS has a hub built in, which allows up to 4 1616FS models to be daisychained together.
And many of the larger digital models (SSR*, ERB*, PDISO8)
also have a hub built in, allowing 10 or more to be daisychained together Note also that many PCs have more than one USB root controller, or you can add another via a PCI, PCIe, or PCexpress Card to USB adapter. Newer models tend to have faster A/D and D/A performance specs, and thus simply enumerating properly may not guarantee max data rate performance.
However, such
performance limits are unlikely to be reached, as we have tested 4 USB-25xx series (1 MHz A/D per board) and 4 USB-1608GX (500 KHz A/D per board) at full speed, with no performance issues. While not common, power can also be an consideration, since some models take their power from the USB bus. Such models will draw less than 500 mA each, and the PC (or hub) is supposed to be able to provide this for each port. This is generally not an issue on desktop PC, though laptop PCs may require an externally powered hub.
Measurement Computing Data Acquisition Knowledgebase http://kb.mccdaq.com/KnowledgebaseArticle50341.aspx
