 How to make PCI-6534 read a voltage of 200mV |
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 Aug 21 2005, 10:07 AM
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More Active  Member Posts: 35 Joined: 7-August 05 Member No.: 2711 LV:6.1 
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Dear all,
Is it possible to make PCI-6534 to read the input which is around 200mV? I read the datasheet which is available on ni.com and it says that PCI-6534 is 5V TTL. Does it mean that there is no way for it to trigger a reading as long as the voltage is smaller than 5V? Thank you very much for your attention!! Ayumi
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Aug 21 2005, 10:07 AM
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Aug 22 2005, 11:39 AM
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 Very Active Member Posts: 236 Joined: 16-April 04 Member No.: 360 Using LabVIEW Since:2006 LV:8.5 ,. ,. 
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QUOTE (ayumisano @ Aug 21 2005, 05:07 AM) Dear all, Is it possible to make PCI-6534 to read the input which is around 200mV? I read the datasheet which is available on ni.com and it says that PCI-6534 is 5V TTL. Does it mean that there is no way for it to trigger a reading as long as the voltage is smaller than 5V? Thank you very much for your attention!! Ayumi  Well since the TTL specification says that a '0' is anything < 0.5V and a '1' is anything > 2.5V, the most straightforward answer is no, you can't trigger a 5V TTL signal with only 200mV. There is most likely a workaround however. Does the 200mV incoming signal meet some kind of spec? What about using a standard RS422/485->RS232 converter? Those use a voltage differential to determine a '0' or '1' where everything between -200mV to 200mV is no man's land, but maybe you could rig a workaround. If you have the abililty to use other hardware it probably won't be a problem to find a workaround, but by itself, I don't think you'll be able to tirgger the PCI-6534 directly.
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Aug 22 2005, 05:21 PM
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 Extremely Active Member Posts: 509 Joined: 2-August 05 Member No.: 2680 Using LabVIEW Since:1996 LV:8.5.1 ,8.6 ,. 
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QUOTE (ayumisano @ Aug 21 2005, 03:07 AM) Dear all, Is it possible to make PCI-6534 to read the input which is around 200mV? I read the datasheet which is available on ni.com and it says that PCI-6534 is 5V TTL. Does it mean that there is no way for it to trigger a reading as long as the voltage is smaller than 5V? Thank you very much for your attention!! Ayumi You could continuously read the input and discard data that doesn't fall within your criteria (200mV or whatever). Neville.
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Aug 22 2005, 07:47 PM
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Very Active Member Posts: 236 Joined: 16-April 04 Member No.: 360 Using LabVIEW Since:2006 LV:8.5 ,. ,.
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QUOTE (Neville D @ Aug 22 2005, 12:21 PM) You could continuously read the input and discard data that doesn't fall within your criteria (200mV or whatever). Neville. TTL is digital, not analog... you can't check voltages in between unless you're doing an analog acquisition.
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Aug 22 2005, 09:49 PM
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 Extremely Active Member Posts: 253 Joined: 15-October 04 From: Phoenix, AZ, USA Member No.: 839 Using LabVIEW Since:2000 LV:8.20 ,. ,.
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You could wire up a comparator chip to output TTL logic levels based on a 200mV threshold.
-------------------- ‘It’s the questions that drive us'
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Aug 28 2005, 06:48 AM
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More Active Member Posts: 35 Joined: 7-August 05 Member No.: 2711 LV:6.1
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QUOTE (AnalogKid2DigitalMan @ Aug 23 2005, 05:49 AM) You could wire up a comparator chip to output TTL logic levels based on a 200mV threshold. Dear all, Thank you very much for your help  Ayumi
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