cFP rs 232 an 485 ports, modbus and OPC

[osvamo]

Hello everyone:

As a general background, my University has 5 cFP systems with the cFP 2020 and several I/O modules (thermocouple, RTD, anlalog output, RLY output, PWM etc.). We also have a departamental LabVIEW 8.0 licence, which doesn't have the RT module; but also we have the departamental LabVIEW 7.1 licence, which has the RTDSC modules.

I have to prepare a lab practice for a Serial-port short course in my University. I think that showing a  cFP 2020 talking to or controlling  S7-200 or S7-300 (SIEMENS) PLCs should be a good idea, since our labs have both technologies. NOTE, the S7 200 and 300 are old PLCs bought aroung 2005.

Another idea is to control an Analog output module or a Relay output module of our cFP systems using the RS 232 an RS 485 ports of the cFP 2020.

Unfortunately, I am just a beginner in all the technical areas involved in such ideas.That's why I am kindly asking you the following:

1- Can I control de cFP 2020, and any I/O module connected to it, through its rs 485 or its rs 232 ports?

2- Or  are these ports intended  to be something like DTEs (using RS 232 terminology), so they are used, exclusively, to control external devices?

3- If the answer to the first question is YES, then Is it possible to control programmaticaly cFP modules (such as analog input, analog output, RLY , etc.) through the RS 232 or the RS     485 ports on the cFP 2020? How can I do it?

  Is there any LabVIEW VI that you may provide me to perform such control? Which cabling (connection interface) is necessary to have the right electrical connections in this case?

4-If the answer to the second question is YES, then Is it possible to control programmaticaly the S7- 200 or S7-300 PLCs through the RS 485 port of the cFP 2020? How can I do it? Can I use the modbus or the OPC servers protocols to make it easier such programming? How can I use such protocols in a targeted VI?

    Is there any  LabVIEW VI that you may provide me to do perform such control? Which cabling (connection interface) is necessary to have the right electrical connections in this case?

5-Is it possible to build a sort of "do it yourself" cabling, made from separate parts, like RJ 50 connectors, 5-pair telephone cables and RS 485 (DB9) connectors?

Thank you very much for your answers.

I apologize if this message resulted too lengthy.

[osvamo]

Sorry for the typo, in the first paragraph I should have said" RT an DSC modules."

Thank you

Best regards

[osvamo]

I should have said "RT and DSC modules" 

Sorry for the double typo.

Best regards

[RavensFan]

With a cFP-2020, you would need to write a VI that executes on the controller.  Many of the Serial port examples would apply just as well to a FP controller as they would for a PC.  The answer would be "yes" you can control the cFP-2020 through the serial port, but you would have write a VI to run on the cFP, read the serial port, and do whatever you need to based on the data it receives.  However, usually if you need to communicate with a cFP controller, you will use the ethernet port, and write a VI to run on a host PC to share data with the VI you have running on the cFP controller.

You can use its serial port to communicate with other devices such as a PLC.  The cFP controller is an intelligent device comparable to a PC, and it can do anything you want based on whatever program you create to run on the controller.

You can do "do-it-yourself" cabling with RJ-50 connectors, wire and DB connectors.  Actually, I found it kind of hard to find RJ-50 connectors, so I just used cables from NI p/n 182845-03.

The one thing to be careful of is that there really is no standard as to what pins mean what for a DB9 connector on RS-485 serial ports on all the devices out there.  So RX+ and RX- pins on the NI cable may be different then the corresponding pins on the connector of the PLC you are using.  Look at the manual for a cFP-2020 controller to see the pin connections and compare it to the devices you are connecting to.

For Modbus, you can use the NI Modbus Library for LabVIEW.

[osvamo]

Thank you very much for your answer. It gave me very useful hints. It  provide me also with good reasons to ask my Department to buying NI cabling.

Sorry  to bother you with more questions, but I am wondering if, in order to communicate two cFP 2020, and since both are DTEs, I would need to use a null-modem connection bewtween their RS-232 ports, as it should be when trying to communicate two PCs. Am I right?

What is the right pin wiring when trying to communicate two cFP 2020 through their RS-485 ports, so that I also get serial communication between such ports?

Thank you for your help.

[RavensFan]

So two cFP-2020's talking back and forth to each other through the RS-232 ports?  Then yes, you will need a null modem cable or adapter in between.

For RS-485, look at http://www.ni.com/pdf/manuals/370708b.pdf page 3-9.  If you look at the first FP-1000 as being your second cFP-2020, and ignore the other FP-1000's in that drawing, it should be what you want.  Basically you need to connect the RX pair on one with the TX pair on the other, and vice versa.

[osvamo]

Thanks a lot! Your answers have been very valuable!

I appreciate your time and help!! I'll try to keep you posted about the trials I am about to do, following your advise, of course.

Sorry if I am answering a little bit late. I´ve been taking care of many other duties in my University.

[Anupam]

Hi RavensFan,

I am trying to read data from a flowmeter that interacts using RS 485. I am using cFP-2000 and I want to use the serial port on the cFP to acquire the data. I used a RS 485 to RS 232 convertor to plug the flow meter directly in the cFP-2000.

From several forums, I have realised that the VI should run on the controller.

I have also installed Modbus library for Labvie, but I dont have much understanding how should I go about read/write on the serial port.

Can you guide me to resources that will help me developing this VI.

Regards,

Anupam

[Sajeesh]

hii...

use a converter RS 485 to RS 232 (ADAM 4520 converter) and plug it to cFP 2000 COM port.Use serial port communication vi such as VISA configure Serial Port,VISA bytes at Serial Port,VISA read,VISA close.Plese give the correct parameters..such as baud rae in VISA configure serial port....