Set extended attributes for
Modbus
 collection

Control the manner in which data is controlled and interpreted over
Modbus®
communications.
TIP: Extended attributes are only available for variables with a
Modbus
 address. Specify the
Modbus
 address format (
Hexadecimal
or
Decimal
) in the CAM
Trusted
 settings from the
Tools
>
Options
menu. The
System Configuration Tool
 reads
Modbus
 addresses for variables in Decimal format.
  • Write Protect
    : Inhibits external communications from overwriting a data point. This applies to both Integer/Real and Boolean variables.
    To force compatibility of read/write capabilities of coils and registers for the current
    8110
    Trusted
     TMR Processor
     with previous firmware versions, when configuring the processor, in the
    Updater
    section, select the
    Auto Protect Network Variables
     check box. The compatible read/write capabilities of the coils and registers are the following:
    Address
    Element
    Number of Elements
    Capability
    00001 – 7500
    Coils
    (7500 coils)
    Read only
    07501 - 10000
    Coils
    (2500 coils)
    Read/write
    40001 - 47500
    Holding registers
    (2500 holding registers)
    Read only
    47501 - 50000
    Holding registers
    (2500 holding registers)
    Read/write
  • Registers as Unsigned Integer
    : Reads and writes
    Modbus
     data as unsigned data. Integer data is normally treated as 32-bit signed within the application (for signed data, the most significant bit is used to distinguish positive and negative numbers).
  • Use Two Registers (32-bits)
    : Uses two contiguous
    Modbus
     registers to transfer all 32 bits. By default, only the lower 16 bits of an analog data point are transferred to and from the
    Modbus
     communications.
  • Least Significant Word First
    : Reverses the words on the
    Modbus
     addresses. If
    Use Two Registers
     is selected, by default the most significant 16-bit word is addressed first on
    Modbus
     communications.
For details on extended attributes for
Modbus
 variables, refer to the Product Description PD-8082,
Trusted
 Toolset Suite.
To set extended attributes for
Modbus
 collection
  1. In the
    Dictionary
    , select the variable, then set
    Modbus
     Address
    .
    TIP: The
    T8151 Communications Interface
     does not support duplicate
    Modbus
     addresses.
  2. Click
    OK
    .
  3. In the
    Application View
    , right-click the dictionary instance and click
    Extended Attributes
    .
  4. In the Appli.vxa window, select the
    Modbus
     tab, then select one or more of the extended attributes for the variable.
    TIP: The
    Least Significant Word First
     option is grayed out unless the
    Use Two Registers
     option is selected.
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