Error -201062 when performing continuous reading of a Digital Input

[LaurenceBunnage]

I am currently using a PCI 6251 to control some hardware and monitor it's status.

I have two analogue inputs on AO/line0 and AO.line1, two analogue outputs on AI/line0 and AI/line1.  Originally we had a continuous digital signal on port0/line0.  This configuration worked fine.

Due to some electronic changes, the system has been changed so that two new digital outputs were added at port0/line0 and port0/line1.  It was decided to move the didgital input to port1/line0.  With this configuration, we get an error reading the digital input, specifically Error -201062, which I believe to be a buffer operation error.

Setting us this same configuration using Measurement & Automation explorer gives me the same result.  I can fix the error on Measurement & Automation error by moving the digital input back to any channel on port0.  Due to logistical reasons, we are also trying to keep outputs on one port and inputs on another.  Also, to move the input channel would also require relaying the board again, so I am reluctant to have to do this unless it is really neccesary.

I can find very little documentation regarding buffered operation, especially which channels do and do not support it.  The specification for the PCI 6251 simple says buffered operation is supported, but not which channels do and do not support it.  Also, is it possible to configure which ports are set for buffered operation and which are not.  I cannot see any function which would do this, but you may have other info unavailable to us.

As this is a project in development and it is expected that we will be extending the hardware at some point in the future, could you please let us have more infomation on this.

[hannahW]

Hello,

The definition of Error -201062 is "Measurements: Selected lines do not support buffered operations". This is because you are trying to perform a timed operation on a digital line which does not support this.

All M Series boards have the capability to perform correlated digital I/O which allow you to generate or acquire hardware timed digital waveforms. This is only possible using Port 0 of these devices.

Looking at the product page for the PCI-6251, the summary explains that the device has "Correlated DIO (8 clocked lines, 10 MHz); analog and digital triggeringCorrelated DIO (8 clocked lines, 10 MHz); analog and digital triggering"
http://sine.ni.com/nips/cds/view/p/lang/en/nid/14124

The M Series User Manual, also gives details on digital waveform acquisition and generation, and explains that it is only available on port 0. So depending on the number of lines your device has on port 0, it will determine how many clocked digital channels that you can have. In the case of the PCI-6251, there are 8 lines.
http://digital.ni.com/manuals.nsf/websearch/9F6B44D406AE5C6E86257221006EE8A5

Also - the specifications of the device give this information, in a similar format :
http://digital.ni.com/manuals.nsf/websearch/64B7323DE2FA2CD9862572260058BC7A

So you will need to make use of Port 0 to perform buffered digital I/O. There is no function which allows you to select which port you will be able to use for this.

There is more information on M Series generally, and the functionality of these devices on our website at the following location:
http://zone.ni.com/devzone/cda/tut/p/id/3614

I hope this helps, please let me know if you have any questions

Regards
Hannah
NIUK & Ireland