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AlexUT

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Posts posted by AlexUT

  1. Hi,

    About how Ladder and PLC program works:

    PLC contineously scan ladder code from up to down and from left to right.

    All Inputs are read before the start of the first net processing.

    All Outputs are updated after the last net processing.

    So at the time you wants to use some Input result - it is already known.

    Immediate Read operation allowed only for High Speed Inputs.

    In your case these inputs are 0 to 5.

    So there are right messages for inputs 6 and up.

    Now question - why you use Immediate Read?

    Do you really need this in your first project?

  2. Hanna,

    It will be better if you describe in more details connection between modules.

    When you use IO-PT4K, you should use either EX-A1 or EX-A2X Expansion Adapter with a proper cable between it and OPLC.

    Cables are different. Cable for EX-A1 has Gray connectors. Cable for EX-A2X has Yellow connectors. Connector with a Groung wire should be connected to OPLC.

    IO-PT4K module should be connected to Expansion Adapter with a cmall flat cable.

    EX-A1 or EX-A2X Expansion Adapter should pe powered from Power Suply.

    Please tell if everything i wrote is implemented.

  3. Hi Hanna,

    There are two I/O Expansion modules,I/O Expansion module IO-PT400 for PT100, and I/O Expansion module IO-PT4K for PT1000.

    In VisiLogic Hardware Configuration there is a common I/O Expansion module IO-PT4X.

    VisiLogic know to detect which modul is in use.

    So when you use PT1000, you should use I/O Expansion module IO-PT4K .

    See attached picture, where I measure a temperature of hot water.

    post-5711-017368800 1325059568_thumb.jpg

  4. Hi Danny,

    I am sorry for missing your request for help.

    Was the problem solved or you need further help?

    * PLC can not answer to any HyperTerminal input as by default it use VisiLogic communication protocol.

    ** To check cable or adapter, you need to shortcut pins 2 and 3 at 9 pin RS-232 connector.

    Entering any symbols from HyperTerminal will echo back.

  5. Hi Dan,

    You need allocate memory for a maximum characters in string + 1 for <0> (null) terminator.

    SMS message will be shortest, but allocated space will warrant that any message will be processed.

    If you use your own algorithm to process SMS - I will recommend you to work with Data Table, where you will define fields, one or more if you need.

    There is a set of operations with a table rows, which will simplify you task.

    Standard SMS functions have 16 strings with a fixed SMS messages structure.

  6. Hi Ron,

    As stated in document , "Conversion time 100mSec minimum per input in Normal mode", "Conversion time 25mSec minimum per input in Fast mode".

    So for 8 Analog Inputs in a Fast mode conversion time will be 25mSec*8=200mSec.

    As IO-AI8, communication between it and OPLC, and OPLC itself works without synchronization, you need to add communication time ~20 mSec and OPLC scan time as Emil stated.

    The other forum topic discussing the same issue will be interesting for you:

    http://www.unitronics.com/forum/topic.asp?TOPIC_ID=1362

  7. Hi bender,

    I recommend you to start from Data Tables Webinar:

    http://www.unitronics.com/Content.aspx?page=datatables

    Please note, you can exchange data between SD card and Data Table at OPLC:

    -Use Data Table functions;

    -Use SD Data Table functions;

    -Note that the main DT folder and subfolders DT1, DT2, DT3, DT4 can each contain 64 files, for a total of 320 .udt files.

    This way you can handle up to 320 files on SD card.

    You can then read information from SD files to OPLC memory.

    You can use also SD function Block Read/Write , but it seems a little more complicated.

    Answer may be more specific if you provide more information about your project requirements.

  8. Hi julle,

    I recommend you start from Examples of Visilogic.

    Shortest way to open Examples is to go to "Help->Examples...) menu option.

    Then go to "Version 900->Project examples" directory.

    "V280_ON_off_control_with_hysteresis_and_high_and_low_alarms.vlp" project was written for heating control with hysteresis.

    This project will be adopted to control Pump.

    "V120_Variable_enter_control.vlp" project is a simple example fo Variable entry control.

    I hope this answers your questions.

  9. Hi Clive,

    To get the most accurate measurement we highly recommend to use 3-4 wire RTD sensor.

    Using 2 wire sensor may lead to very unstable (sensitive to noises) and un-precise (affected by wire impedance) reading.

    If anyway you have two wire RTD sensor, you need to connect one of the wires to T+ and T- (both have PT label as well) and the second wire connect to CM.

    You need to define selected input as PT100 in hardware configuration in accordance to used PT100 type (alpha=0.0385 or, alpha=0.0392) assign MI and select C(celsius) or F.

    Then you will see in assigned MI raw number, which is 10xt.

    Example: you see raw number 247. Temperature is 24.7 C.

    When MI = 32767 Sensor is not connected to input, or value exceeds permissible range,

    or sensor is different than PT100 (for example, PT1000).

    When MI = -32767 Sensor is short-circuited

  10. Hi Manville,

    Do you have any fan driver or just fan with two wires?

    What is a fan current?

    To drive a fan voltage, you need additional driver, as an analog inputs and output of M90-TA2-CAN is 0-10V.

    Analog output have 1Kohm minimum load impedance.

    This means that the max current you can obtain theoretically at 10 V is 10 mA.

    Seems far below the one you need to drive any kind of fan motor.

    *Digital Output have current limit 0.5A, but you need realise PWM, as Joe say.

    Be more specific with your specifications, then answers will be fastest and more specific as well.

    Best regards,

    Alex.

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