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Overview: Data Display Panel

The Data Display Panel (DDP) is that area of the Data Group Form in which the data acquired from the Modbus device is displayed. The DDP:

  • displays formatted data as per the current format selection.
  • can be used to change the value of a single Modbus variable at a time (using WriteSingleCoil and WriteSingleRegister function codes)
  • Note:
    The display for each Modbus address has two components. The address field and the value field. The address field is always displayed in decimal irrespective of the selected data format and is prefixed with the data type code as defined by the Modbus standard.
  • 1 for Discrete Inputs
  • 2 for Coils
  • 3 for Input Registers
  • 4 for Holding Registers
  • In what format is data displayed?

    Coils and Discrete Inputs are always displayed as binary values - '1' if the Coil/DI status is Hi or '0' if Low. However register data is displayed in one of the following formats:

  • Hexadecimal (as 2-byte value). E.g. 0x8ABC
  • Short Integer (2-byte signed decimal value). E.g. -30020
  • Unsigned Short Integer (2-byte unsigned decimal value). E.g. 35516
  • Integer (4-byte signed decimal value). E.g. 12345678
  • Unsigned Integer (4-byte unsigned decimal value). E.g. -12345678
  • Float (4-byte IEEE 754 single precision real value). E.g. 124.35
  • Double (8-byte IEEE 754 double precision real value). E.g. 124.35
  • How to change the data display format?

    The format can be changed using one of two ways:

  • Using the toolbar button
  • 1. Select the Data Group Form whose data format is to be changed by clicking anywhere on the form.
    2. Click the "Change Display Format" toobar button. A drop down list box appears as below showing the current format with a tick mark.
    3. Select the desired data format by clicking a relevant list item.
  • Using the right-click pop-up menu
  • 1.Right-click on the Data Display Panel of the Data Group Form whose data format is to be changed. A pop-up menu appears as shown below showing the current
    format with a tick mark.

    2.Select the desired data format by clicking a relevant pop-up menu item.
    How is data displayed when no data is being polled or when an active connection is dropped while polling is in progress?

    When a Data Group is first created and has not yet acquired any data from the device, the value fields for all configured addresses show question marks "?????" to indicate that they do not have data worth showing. However, if atleast one data set was acquired and then the polling was stopped, the DDP will display the last acquired data for all the addresses. However if a connection is dropped when polling was in progress, the display changes to "?????".

    Freshly opened Form Polling Off but atleast one data set acquired Connection dropped while polling

    See Also

    Topic link How To: Change values of Modbus variables from Data Group Form
    Topic link How To: Customise the look and feel (UI) of Data Group Forms
    Topic link Learn more about Modbus Data Group Forms
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