© National Instruments | 3-5M Series User Manual+5 V Power SourceThe +5 V terminals on the I/O connector supply +5 V referenced to D GND. Use these terminalsto power external circuitry.Newer revision M Series devices have a traditional fuse to protect the supply from overcurrentconditions. This fuse is not customer-replaceable; if the fuse permanently opens, return thedevice to NI for repair.Older revision M Series devices have a self-resetting fuse to protect the supply from overcurrentconditions. This fuse resets automatically within a few seconds after the overcurrent conditionis removed. For more information about the self-resetting fuse and precautions to take to avoidimproper connection of +5 V and ground terminals, refer to the KnowledgeBase document,Self-Resetting Fuse Additional Information, by going to ni.com/info and entering the InfoCode pptc.(USB-6281/6289 Devices) All USB-628x devices have a user-replaceable socketed fuse toprotect the supply from overcurrent conditions. When an overcurrent condition occurs, checkyour cabling to the +5 V terminals and replace the fuse as described in the USB Device FuseReplacement section of Chapter 1, Getting Started.Caution Never connect the +5 V power terminals to analog or digital ground or toany other voltage source on the M Series device or any other device. Doing so candamage the device and the computer. NI is not liable for damage resulting from sucha connection.The power rating on most devices is +4.75 to +5.25 VDC at 1 A.Refer to the specifications document for your device to obtain the device power rating.Note (NI PCIe-6251/6259 Devices) M Series PCI Express devices supply lessthan 1 A of +5 V power unless you use the disk drive power connector. Refer to theGetting Started with M Series PCI Express Devices and the Disk Drive PowerConnector section of Chapter 1, Getting Started, for more information.Note The NI 6221 (37-pin) device does not have a +5 V terminal.USER 1 and USER 2(NI USB-622x/625x BNC Devices) The USER connectors allow you to use a BNC connectorfor a digital or timing I/O signal of your choice. The USER 1 and USER 2 BNC connectors arerouted (internal to the USB BNC device) to the USER 1 and USER 2 screw terminals, as shownin Figure 3-1.Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com
