Datatype of MXIe or cRIO-903x/4x User FPGA LED

Updated Nov 15, 2018

Reported In


  • cRIO-9030
  • cRIO-9031
  • cRIO-9032
  • cRIO-9033
  • cRIO-9034
  • cRIO-9035
  • cRIO-9036
  • cRIO-9037
  • cRIO-9038
  • cRIO-9039
  • NI-9154
  • NI-9155
  • NI-9157
  • NI-9159
  • cRIO-9040
  • cRIO-9041
  • cRIO-9042
  • cRIO-9043
  • cRIO-9045
  • cRIO-9046
  • cRIO-9047
  • cRIO-9048
  • cRIO-9049

Issue Details

I'm working with a MXIe-RIO or a CompactRIO 903x/4x. When working with other CompactRIO and Single-Board RIO targets, the FPGA LED was controlled by a Boolean value. However, the FPGA USER LED on my device is represented by an unsigned 8-bit integer (UINT8). Why is it a UINT8, and how do I control it?


Since the LED can be set to three different states, a Boolean data type does not have enough values to represent all the possible states. The values are described below:
  • When USER FPGA LED is 0, the USER FPGA LED is off
  • When USER FPGA LED is 1, the USER FPGA LED is lit green
  • When USER FPGA LED is 2, the USER FPGA LED is lit yellow

Additional Information

The following controllers have a tri-state LED:
  • cRIO-903x
  • cRIO-904x
  • NI-9154
  • NI-9155
  • NI-9157
  • NI-9159