loop timing with Real-Time Communication Wizard

[steve_morris]

I've discovered that the programs generated using the Real-Time Communication Wizard don't work if my TCL timing is set 'too slow'.  The TCL program is a timed loop looking for a boolean to trigger a case structure (I've attached a simplified version) -- depending on the relationship between the TCP read/write loop timing and the TCL timed loop it either works everytime or misses the boolean.  I saw this behavior originally while using a PXI target and having the TCL set to run at 200ms with the default RTCW TCP timing of 100ms.  I've recreated it using the attached programs on a PC target with the following results:

TCP loop timing (ms)/ TCL loop timing

[Richard P.]

Hi Steve,

Since the data is coming first from the OK button, have you tried changing the mechanical action on the button to Latch When Pressed?

I come to this conclusion because TCP communication is buffered, and in addition FIFO's are programmed into the NPL with LabVIEW RT, if the True data was read at any time it should be seen by the TC loop.

Here is a link to information on setting Ethernet port buffer sizes in LabVIEW Real-Time 7.1.1.

http://digital.ni.com/public.nsf/websearch/D8AA40DE5411947386256F5D0061D62F?OpenDocument

Let me know if this helps or if you have additional questions.

Richard

Applications Engineer

www.ni.com/support