May I change counter parameter while it is counting?

Question

Hi all.
I'm using CVI 7.1 and traditional daq with a PCI-6601 board to perform simple event counting to count delays on some tested devices
For my application I need to change the type of counting from ungated to gated while the counter is running: is it possible?
My application is configured this way:
GPCTR_Set_Application (1, ND_COUNTER_0, ND_SIMPLE_EVENT_CNT);
GPCTR_Change_Parameter (1, ND_COUNTER_0, ND_SOURCE, ND_INTERNAL_100_KHZ);
GPCTR_Control (1, ND_COUNTER_0, ND_PROGRAM);
Now, while the counter is running I need to follow on counting only if the gate signal is high. If I simply use
GPCTR_Change_Parameter (1, ND_COUNTER_0, ND_GATE, ND_PFI_38);
I receive the error that "The specified resource is already armed", so I tried with
GPCTR_Control (1, ND_COUNTER_0, ND_DISARM);
GPCTR_Change_Parameter (1, ND_COUNTER_0, ND_GATE, ND_PFI_38);
GPCTR_Control (1, ND_COUNTER_0, ND_ARM);
but the counter continues counting regardless the state of the gate signal. That's why my question: how can I perform this task?
(Note: if configured from start for gated counting, the counter operates regularly based on gate state)
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Answer 1

Kevin, in my application I am monitoring a long-lasting process (approx. 45 seconds long) in which I must measure the time a contact is on. 6601 card is dedicated to measure this time: the contact is used as the gate signal of the counter so that time measurement is exactly related to the process being surveyed. The problem is that during part of this process I cannot be connected to the actual contact, so I cannot use its state as the gating signal during all time.
I was hoping that I could change counter configuration on the fly so that I can start counting based on the gate, switch to ungated counting while I cannot survey the contact and switch back to gated at the end of the interval, when I can use again the contact as counter gate.
In the meanwhile I am monitoring some other parts of the process and acquiring measures on serial (that is intrinsically "slow") devices: due to this sum of processes going on inside the computer, I cannot rely of my program being enough fast as to monitor the state of the DUT and mirror it in a gating signal.
I have tested my solution to sum up partial timer counts and found it not so easy to manage so I decided to introduce a little hardware modification in the measuring system and OR the gating signal with a digital output of the 6601: I can manage in the software to drive this signal with significant margin on actual phenomenon, so that I am now using the counter always in gated mode. This solution is more or less in the way of your last answer seem we arrived at it contemporarily!
Proud to use LW/CVI from 3.1 on.
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If I have helped you, why not giving me a kudos?