LV: Sending "sync message" for getting synchronous CAN acquistion

Question

Hello @ all
First of all: My knowledge about the CAN bus in general is not so good, so excuse a possible unprecise problem description.
My task is to read out CAN messages of devices. This works fine for devices that send their messages "stand-alone" with a fixed repetition rate (here: 100Hz).
But other devices do not send their messages with such a repetition rate. They send their message only until they come in an overflow (here: after 150ms). I´ve heard that I have to send a "sync message" to the devices to get their message. That means, that I have to send the sync message with 100 Hz to get the 100 Hz acquistion.
My question: How should I have to program such a bidirectional CAN transfer? Of course, I can send one sync message and read the answer. But what to do when I want to read for example 10000 messages? I don´t want to trigger it by software due to the timer accuracy.
Do I just have to start the "CAN read.vi" and the "CAN write.vi" parallel? Or is there any possibility to start the write.vi and the read.vi at a fixed time, to get both functions parallel?
Tanks so far.
Solved!
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Answer 1

Hi LittleJoe198,
I'm glad you got it running. 
You are right about the Transmit  Receive same port example, timing is done in software using the wait function.
But the other example (CAN Transmit - periodic) sends the data periodically using hardware timing - specified by the control "Period (ms)". In this case a CAN object is used. Your card supports CAN Objects, so it is very easy to use hardware timing. Take a closer look at your CAN Hardware and Software Manual page 10-19 ff.
"Transmit Data by Call, Receive by Call Using Remote
Period specifies a minimum interval between subsequent
transmissions. Even if ncWriteObj.vi is called very frequently,
frames are transmitted on the network at a rate no more than
Period. "
 Let me know if you have further questions using CAN Objects.
Regards,
Andreas S
Systems Engineer