What Is the Digital Output State of a DAQ Board After Reconfiguring a Port? Hardware: Legacy DAQ Devices>>Digital I/O>>PC-DIO-24
Problem: I am writing a digital pattern to a port on my DAQ board. Will my outputs reset or stay the same after I reconfigure the port? Solution: Whether the digital output state resets or remains the same depends on the type of digital chip on your data acquisition board. There are 4 main chip families to consider: 1) NI-DIO This chip is found on the PCI-653x devices. Reconfiguring the digital port on this card will not reset the outputs. Therefore if you initially wrote a logic high to the line, reconfiguring the port would leave the line high. Similarly, a logic low would also remain the same. 2) NI-TIO This chip is found on our counter/timer PCI-660x devices. Reconfiguring the digital port on this card will not reset the outputs. An output logic high would remain high and a logic low would remain low. 3) DAQ-STC This chip is found on our E Series data acquisition cards. Reconfiguring the digital port will not affect the output state of the digital lines. This case is similar to both the NI-DIO and NI-TIO chips. 4) 8255 This chip is found on our PCI-650x digital data acquisition devices and legacy cards. Reconfiguring the port on this chip will reset all ports on the chip. The KBs linked below have more detail on the specific operation of the 8255 chips. NOTE: This doesn't apply if you change the mode on the line to "read" after the reconfigure. Related Links: KnowlegeBase 0489FD8Q: Why Do All My Digital I/O Ports Reset When I Configure One Port? KnowlegeBase 2L8E72P6: What is the 82C55A and which NI products use this chip? Attachments:
Report Date: 02/20/2003 Last Updated: 02/21/2003 Document ID: 2UJFGV6I |
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