Replacing Digital Line with Network Communications

[sticyfinger]

Hi, 

Does making the timeout for the 'EthernetIP Tag Read' VI zero, remove the ability for the VI to wait? When 'EthernetIP Tag Read' VI poll for the current value of the tag, does it add extra time if wait is zero ms?

I have successful create a code that works using digital signal (see attachment 1). I want to replace some of the digital line with network communication.  Can I just replace digital line SV with 'EthernetIP Tag Read' VI?

The replacement will happen in my non deterministic loop.

[LewisL]

Hi sticyfinger,

Making the timeout for EIP Tag Read.vi zero does not remove the ability for the VI to wait. It shouldn't add extra time.

In my test, it works well wih the timeout set to zero. But given network traffic and stableness, I think you should not set it to zero.

I don't have a clear picture as to how you would use EIP Tag Read in the non-deterministic while loop below, and about the digital line SV, how it was received before, etc.

EIP VI can be used in such a while loop, though.

[sticyfinger]

Thanks

I benchmark the time it take to set a 'Digital line' SV and the time it take to use 'Ethernetip tag Read' VI. The ‘Digital line’ SV take less than an ms and the 'EthernetIP tag Read' VI take about 33 ms.   That mean every time the loop run it will take an extra ~33ms to run any of my states.  

 My initial question was asking how I can have the same level of smaller timing accuracy (similar to the digital line) using the networking communication.  From the benchmarking test I did, I do not think that is not possible. Am I right?

What is a normal timeout time? What is a great way to handle EthernetIP timing out? Can you provide some exaples ?  or link to similar situations. 

[LewisL]

Hi sticyfinger,

Sorry but first I wanna be clear if I uderstand it correctly, that originally you were using an digital output module to transmit the signal on a wire of its own, and you are testing how much time it's taken to set the module, right?

We have done bechmark on read/write bool values using explicit tag messaging. The average times for 10,000 read and write are 20-30 ms. And it still depends on PLC workload and network traffic.

I think that's as good as you could get. The bright side is that you only use one line for communication, right?

Sorry I don't have examples about handling timeout in EIP.  EIP tag msging VIs themselves don't provide machanism for timeout to user application layer. You can wrap the VI in a subVI where you add the timer, etc.