急问：PCI6221的第8pin+5V电源变成0.3V了，为什么？

[daha]

我记得PCI6221第8pin外最多可输出1A的电流，所以我就利用它作为外部一些上拉电阻和芯片的+5V电源（其输出的总电流小于1A）。可是然后我再测量8角的电压，发现只有0.3V了。怎么办？？是不是我把内部电路烧了？？请求各位大侠帮忙解答一下，我实在是不知道为什么。随便问一下，PCI6221第8pin最大输出电流负载是1A吗？如果不是的话，那是多少呢？

先谢了！！！！

[cool_bigben]

建议你和NI技术支持联系，去检测板卡。8PIN输出不是5V是有问题的。

帖子被cool_bigben在09-20-2005 06:46 AM时编辑过了

[Rui Liang]

+5 V Power Source

The +5 V terminals on the I/O connector supply +5 V referenced to D GND. Use these terminals to power external circuitry. A self-resetting fuse protects the supply from overcurrent conditions. The fuse resets automatically within a few seconds after the overcurrent condition is removed.

Power rating (most devices)–+4.65 to +5.25 VDC at 1 A

Refer to the specifications document for your device to obtain the device power rating.

Note  The NI 6221 (37-pin) device does not have a +5 V terminal.

Caution  You should never connect the +5 V power terminals to analog or digital ground or to any other voltage source on the M Series device or any other device. Doing so can damage the device and the computer. NI is not liable for damage resulting from such a connection.

请提供更详细一点信息，关于您对这5v引脚的操作，以便更好的分析。

[Rui Liang]

it seems that the 8 pin +5v has been destroyed. anyway, you should consider the value of up-pull resistor and current, and use multimeter to measure it before connect it.

suggest you to contact NI with above phone number!

regards

[daha]

Thank you very much, Kaoya!!! You are very kind!!

I has contacted NI company with the number you provided today.  So I will send my card to them, they will help me to check it. 

Thanks for your source anyway. 

[Rui Liang]

my pleasure, anyway, if you get problem or any doubt, just call them and they'll give you suggestion or idea to solver your problem.

regards

[moto_zhang]

你的卡在MAX裡面自檢pass嗎？建議：不要用ni卡上內部vcc作外部電路的vcc。