Problem with simultaneous AI and DO tasks: Error -89137

[ArunJ]

I have a PXI system with two X-series PXIe-6345 modules. I have to create an AI Countinuous Sampling task, to acquire data from channels in these two modules, which runs fine. Then my application requires to to create a DO task and Counter task some time later, when the AI task is running. But I get following Error:

Error -89137 occurred at Test_DO_Write chn.vi

Possible reason(s):

Specified route cannot be satisfied, because it requires resources that are currently in use by another route.

Property: RefClk.Src
Source Device: PXI1Slot2
Source Terminal: None

Required Resources in Use by
Task Name: _unnamedTask<53>
Source Device: PXI1Slot2
Source Terminal: PXIe_Clk100
Destination Device: PXI1Slot2
Destination Terminal: RefClockInternal

Task Name: _unnamedTask<51>

(unnamedTask<51> is DO task and _unnamedTask<53> is AI task in the above message)

I get this error whenever I try to create a new DO or Counter task in the same 6345 module, during an ongoing AI acquisition.It looks like the DO task is trying to access the Int.Ref.Clock line, to which a 100MHZ clock is already routed for the AI task. I tried to assign this 100MHZ clock, as Ref. clock for the DO task, using propery node. But it returns error indicating 'harware not supported;. 

I am attaching a VI to explain this issue.

[ArunJ · Accepted solution]

The proble has been resolved. By setting the PXI 100MHZ backplane clock (PXIe_Clk100) as the reference clock for both AI and DO tasks, using DAQmx Timing property nodes "ReferenceClock.Source" and ReferenceClock.Rate", things are working properly.