[Screen Navigation by Number]

I think you can write the Display Number into SI252 to go to that display.

[Can't connect to v570 via ethernet]

Thanks for your reply. Since I'm not connected through a router or network, I'm not sure the Default Gateway really matters, but I've tried a number of different settings, all to no avail. The two PLCs and the laptop PC are connected through a digital switch, not a router. I've also tried connecting the PC directly to one of the PLCs with a crossover cable, but that doesn't work either. Again, PING works fine, just can't connect using VisiLogic.

I have no anti-virus or firewall running right now (not connected to the internet) - any other settings I should be looking at? What are the minimum requirements to connect VisiLogic to a PLC via Ethernet?

-PLC Name

-PLC Port #

-PLC IP Address

-Protocol: TCP

-Socket initialized to TCP Slave

-PLC & PC on the same subnet

Those are all I can think of and I've checked and re-checked all these items. What am I missing?

[Can't connect to v570 via ethernet]

I'm suddenly having a problem that I can't figure out. I hope someone can provide a few tips. I am trying to connect to a couple of v570s via ethernet from my laptop. I've never had a problem doing this in the past but suddenly something is broken. I have two v570s successfully talking to each other through an ethernet switch using MODBUS IP. When I connect my laptop to the switch I can ping either v570 successfully, but I cannot connect to either using VisiLogic. I have the PLC Names set properly, have the correct port number, and IP addresses entered into the communication box, but no go. Here is the setup on each PLC:

PLC Master - Socket 3 initialized to Port 502, protocol TCP, Master, for PLC-PLC com (IP Address 10.1.1.101)

Socket 1 initialized to Port 20256, protocol TCP, Slave, for PLC-PC comm

PLC Slave - Socket 2 initialized to Port 502, protocol TCP, Slave, for PLC-PLC comm (IP Address 10.1.1.102)

Socket 1 initialized to port 20256, protocol TCP, Slave, for PLC-PC comm.

PC - IP Address set to 10.1.1.100

All three are set to 255.255.255.0 for subnet mask, and 010.255.255.255 for Default Gateway. System bits on both PLCs show both sockets on each PLC to be initialized, as well as the ethernet card.

I'm sure I'm overlooking some silly little thing - what is it?

Thanks.

[UDP conflict with TCP?]

Thank you! That gives me great peace of mind.

[UDP conflict with TCP?]

I have used Unitronics PLCs networked using both UDP, when networked independently from the customer network and MODBUS IP when connected to the customer network. My networking knowledge is somewhat limited and I now have an application where I would like to use UDP because I will be networking up to 30 PLCs, but do not wish to work through opening and closing ports so many times. This project must reside on the customer's network. Will the PLCs running UDP cause problems for my customer's standard TCP protocol network?

[Need PID help]

Emil, just wanted to let you know that I was able to test using your suggestions over the last few days and it seems to be working well. Thank you very much for your outstanding assistance.

[Need PID help]

Thank you for the quick response! I will try all your suggestions and get back to you.

[Need PID help]

Thank you, Emil - that helps a lot.

Just to make sure I understand, you do not think Autotune is necessary for a pressure control scenario? I will add that the process will involve dramatically changing demand and the intent is to try to keep it steady by varying the pump.

As far as where I want to perform Autotune, I don't care - whatever will provide the customer the most trouble-free operation. I haven't been able to get the PID Server to actually exchange data with the I/O, even though I was able to get it connected and online to the PLC.

Perhaps it was the starting values I was using for some of the configuration variables, but I was having a big problem with the PID control acting as a "switch" rather than smooth control. Once the target was reached, the pump would immediately drop to the minimum (CV Low) and when the process input dropped below target the pump would immediately go to maximum (CV High). After a few cycles of this the PID control would stop working and give a Status value of -7. I will be trying again with your recommendations and with a better understanding based on your reply.

Even assuming I can overcome the "switch" behavior, I want the PID control to be able to recover automatically in the event of an error. Can you suggest actions I should take to automatically initiate recovery if there is a PID control error?

[Need PID help]

I have limited experience with the Unitronics PID function and desperately need some help. I am using a V570 with an IO-AI4-AO2 I/O Expansion and VisiLogic 8.6.3. I am connecting a pressure sensor (4-20ma) to AI0 and controlling a pump on AO0, also with 4-20ma. I have set up a PID control loop using the example file in VisiLogic, but some of the configuration MIs are a bit confusing. Can someone provide a common sense explanation for some of the less obvious ones? For example, the PV high and low limit - what are these values doing? I understand the limits on CV, but not PV.

Also, I am unable to get the Autotune PID Server to work properly. I was able to get it online with the PLC with all the MIs set, but when I run the Server, nothing happens - there is no data exchange with the I/O module. Any helpful hints?

Lastly, this is an extremely simple control loop and could probably work well with proportional control only. Can I & D be turned off? Either way, what are some basic starting values I should input into the configuration MIs to at least get me down the road to tuning the control loop?

[Question about Create Excel Delimited Line FB]

Okay, I'm dumb - it looks for a NULL character. Sorry for the confusion.

[Question about Create Excel Delimited Line FB]

Thanks, but that appears to provide the TOTAL length of the Excel line being created. How does it know the length of the INDIVIDUAL vectors that make up the line? Or is there something I'm totally missing?

Looking at the example project, (V570_DS_card_demo.vlp), Field #1 is Date to ASCII (vector of 5 MIs) and Field #2 is RTC to ASCII (also a vector of 5 MIs), then there are 2 Numeric Fields. The Indirect Text MIs (MI500 & MI510) are each LABELED as being vectors of length 5, but how does the FB know they are vectors and what the length is?

[Question about Create Excel Delimited Line FB]

There is something about this FB that I don't understand that isn't addressed in the Help file nor in the recent webinar on this subject. Looking at the Project Example for SD cards, when you open the "Create Excel Delimited Line" function there are 4 fields defined (MI500, MI510, MI508, & MI509). The "Size (in chars) column shows an "*". Why is that? Since this field is a vector of 5 MIs, where is that indicated to the function to grab 5 MIs rather than just 1 (i.e. where is it being told that MI500 and MI510 are vectors of length 5?)

[Help needed with challenging algorithm]

Thank you very much, Emil. I will spend a couple of days looking at this and get back to you.

[Help needed with challenging algorithm]

I have an odd customer request that has me stumped as to how to program this efficiently - perhaps someone here can help.

I am using a v570 PLC to control 10 valves. I have 10 demand digital inputs (requests to open individual valves) and 10 digital outputs to open and close the valves. The pump that pushes chemical through these valves is not capable of handling more than a few open valves simultaneously, also some of the valves are more important than others. So, the customer would like an input on-screen to adjust the number of valves that can be open simultaneously and a priority selection for any or all of the valves. If there are more than the input value number of valves being requested to open simultaneously, then additional valves should be held off until an open valve closes. Valve opening should be in FIFO order with priority valves taking precedence.

The biggest problem I'm having is trying to deal with the FIFO (i.e. maintaining a continuous and current hierarchical list of valves waiting their turn to open) and for dealing with the conflict that allows the priority valves to move to the head of the line.

Can anyone suggest the basic framework of an algorithm that will accomplish this in VisiLogic?

Thank you for your help.

[Image Library]

Even though I had originally installed VisiLogic from a link on the website and then tried to re-install from the CD that came with one of my V570s, all I had was an empty folder where the images should be. I tried to re-install again from the link in your reply (directly above) and the folder is now populated as it should be. I'm not sure what the problem was before, but I have my image library now. Thanks.

[Image Library]

I've seen many posts in the forum (old forum) and mention in the Help file about an image library that is supposed to be installed with VisiLogic (at C:\Program Files\Unitronics\Unitronics Visilogic_C\Data\ImagesC), but all I have is an empty folder. I tried re-installing VisiLogic, but no change. I checked the CD that came with a V570, but there is nothing there. I've searched the Unitronics website, but there is nothing there. Where is this Image Library???