Unable to Set Certain Addresses in NI-FBUS Configurator

Updated Aug 19, 2022

Reported In


  • NI-FBUS Configurator Software
  • NI-FBUS Communication Software



Issue Details

I am requiring to assign certain address for my device in the FBUS configurator. However, my desired address is not listed in the selection. For example, address from 37[0x37] to 222[0xde] is not visible in the range of addresses. Why are some addresses missing and how do I set them to my device?


The Fieldbus specification defines the Link Active Scheduler (LAS) device to poll a list of addresses by sending a Probe Node (PN) packet to each address in its list of addresses. This allows devices to come online during normal operation. The specification also describes how to tell LAS to skip probing certain addresses in the range in order to speed up the new devices detection on the bus (or devices that are having their addresses changed).

The two parameters involved in maintaining the unpolled region in the list are called:

  • FirstUnpolledNode (FUN): tells the LAS the beginning of a region of addresses not to probe
  • NumOfUnpolledNodes (NUN):  tells the LAS the length of that region

These parameters can be modified by opening the Network Parameters under the link interface and selecting the Link Settings (Advanced) tab. Change the FUN and NUN value to allow specific addresses to be assigned to the device.