Routing Considerations for AO Series Devices

The following sections detail special routing considerations for AO Series devices.

Counters

The counters on AO Series devices are very versatile and in many cases can route signals across subsystems. They can also be used to route signals to/from the I/O connector. However, when a counter is used as part of a route, you may not be able to use the counter for other applications while the route remains reserved. Most routes do not require an internal counter terminal, but many advanced routes do. For example, if you want to use the signal present at PFI 4 on Dev1 as the Start Trigger for an acquisition on Dev2, you simply need to specify /Dev1/PFI4 as the source of the trigger. However, to make the route, the signal is internally routed from /Dev1/PFI4 to /Dev1/Ctr0Source to a RTSI bus line or PXI_Trig to Dev2/ai/StartTrigger. These terminals need not be explicitly specified when programming the route. In this case, it is not obvious that a counter terminal is used to make the route. Subsequent attempts at using the counter while it is in use result in a routing reservation error. To see if the route you are making uses counter resources, consult the table displayed under the Device Routes tab in MAX.