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dierkens

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Posts posted by dierkens

  1. Maximizing Modbus masters using the UAC-02RSC

    in UniLogic Software

    Posted

    So let me get this straight; you're going to poll 256+ modbus items over 3 serials ports that will have 512+ operations over a 232/485 serial port?

    In the standard MODBUS network there is one MASTER and up to 247 slaves.  

    I would not want to be in the shoes of the startup engineer on this project.  Yes, it can be done.   Yes, you may not be up against the serial limitations, however you're going to have a troubleshooting nightmare if just one of those devices on causes a conflict you're in a fun week or two or six...   

    Enough of that.

    Let's start at the beginning:   Read this and see if that fills in any gaps you may have missed.

    Modbus Over Serial Line V1.02

    Are you using a MODBUS Gateway at all?

  2. Modbus TCP, check forwarded data

    in UniLogic Software

    Posted

    51 minutes ago, ORSO2001 said:

    hi dierkens

    thanks for answer....maybe my explanation was not clear...my PLC works as a slave...i create some registers (read, write) for a master (that is not mine)...who has created the master program is saying me that the communications is not working...but if i use a program test to check my registers all works fine...i need to know what they are passing me.

    You should use something like a MODSCAN to test the reading/writing of registers/coils on both ends.

    Although you indicate that your PLC works as a slave, you must mean that they are sending the MODBUS register information to your PLC.

    You can use WIRESHARK to get down to the packet level of information; but that level of detail typically isn't needed.

    1. Can you ping the MASTER device?
    2. Can the SLAVE ping you?
    3. Have you checked the OFFSET to make sure that both devices are using the same array start [Zero (0) based versus One (1) based register assignments].  Start with something easy like coils or a lower register.  

    Just use some basic MODBUS troubleshooting techniques.

  4. I/O Specification Equivalents

    in UniStream: Hardware

    Posted

    9 hours ago, Joe Tauser said:

    UniStream does not have isolated differential analog inputs or outputs, and the resolution is not quite as high.  You need to determine if this is important. 

    I'm betting the UniStream I/O is a lot lower cost.  Are all the sensors powered from the same supply?  Are they 0-10V, 4/20mA, or something else?

    Joe T.

    They're a mix of 0-5v; 0-10v; with the majority of them 4-20mA.

    8 of the inputs are from the same source (a DCS); there's 6 separate Voltage Inputs and 17 separate mA inputs.

    I've got two (2) choices; either purchase some isolation modules (at a cost of about $75/input) or use another companies I/O products that are isolated.

    Are there any other non-Unitronics modules that you'd recommend?

  6. I/O Specification Equivalents

    in UniStream: Hardware

    Posted

    I've got a project where we're trying to replace a customers existing Emissions Monitor data logger.  

    I'm trying to match the specifications of their current products to the equivalent Unitstream I/O products.  I've looked at the specification sheets for all of the I/O module and I'm not seeing a direct correlations between some of them.  What's the best way to post up the specs of the existing I/O to see if you guys can help me match it.  Here's an example of the Current Input Cards of the existing controller.

    I tried to post the specs here in the post itself but I couldn't lay it out nicely; so there attached.  

    Any help is really appreciated.

     
     
     
     
     
     
     
     
     
     

     

    Existing Controller IO Card Specifications.pdf

  7. Modbus periodic update interval "problem"

    in UniLogic Software

    Posted

    3 hours ago, Joe Tauser said:

    100 ms updates are quite fast for 9600 baud.  There's a lot of overhead involved with generating a Modbus frame and the time you've selected is not realistic.  My experience has been 1 second updates are about the best you can do, as you've proven.

    Have you tried dialing up the baud rate to 115K?  Are your devices capable of it?

    Joe T.

     

    This is exactly what I was going to ask.  Your update rate will always be limited by the speed of your serial port and how much data you're getting from the devices.

    Crank up that baud rate on both ends and see what happens.

  10. Mobus reading and writing Double words third party

    in UniLogic Software

    Posted

    2 minutes ago, hotwires said:

    serial or TCP/IP MODBUS? 

    300001 and 400001 (decimal) are a typo?

    An extra zero? Max analog write address appears to be 49,999

    I was thinking the same thing.  

    I sure hope it was a typo...

    I can't believe anyone would set up a program that interpolated  them with that range.

    One thing he may want to try is get Modscan or equivalent and test it real quick.

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