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Not all arbitration options take the same amount of time to execute. If you want accesses to multiple resources of the same type to occur simultaneously, you must choose arbitration options for each resource that take the same amount of time to execute. The following figure illustrates an FPGA VI that might have a timing problem depending on the arbitration options selected.

The FPGA I/O Nodes shown in the figure above have three arbitration options. If you choose the Always Arbitrate arbitration option, LabVIEW implements an equivalent arbiter for both Connector0/DIO0 and Connector0/DIO1. Both arbiters take the same amount of time to execute, so Connector0/DIO0 and Connector0/DIO1 output simultaneously in the first frame of the Flat Sequence structure, as long as another object elsewhere on the block diagram does not simultaneously request access to either Connector0/DIO0 or Connector0/DIO1.

If you choose the Arbitrate if Multiple Requestors Only arbitration option, LabVIEW implements an arbiter for Connector0/DIO0 but does implement an arbiter for Connector0/DIO1. Connector0/DIO0 uses an arbiter because the block diagram requests access to Connector0/DIO0 twice. Connector0/DIO1 uses no arbiter because the block diagram requests access to Connector0/DIO1 only once. Connector0/DIO0 takes longer to execute than Connector0/DIO1, so Connector0/DIO0 and Connector0/DIO1 do not output simultaneously in the first frame of the Flat Sequence structure.

If you choose the Never Arbitrate arbitration option for both FPGA I/O Nodes, LabVIEW does not implement an arbiter for either Connector0/DIO0 or Connector0/DIO1. Therefore, Connector0/DIO0 and Connector0/DIO1 output simultaneously.