Creating Modbus Variables

As part of defining a Modbus Custom Slave, you need to set up the Modbus variables read by a Modbus frame.

Click New item to create a new variable, and fill in these different fields:

Field	Description	Comment
Name and Unit	Enables you to select a variable name from the Name list. This variable name determines the Unit options.	You can select Customized in the drop-down list and type a new text string for the name field and the unit field.
Format	Specifies the format of this number.	Several formats are available as described in the table below.
First register address	Specifies the first register number.	The register number must belong to the range of the frame. If the format contains more than 1 register, the setting checks that the last register used by this measurement is inside the frame content.
Factor	The displayed measure = (transmitted value x factor) + offset.	The displayed measure is the value displayed in the measurement tables. Transmitted value is the measure done by the meter.
Offset
Invalid value	Indicates the transmitted value is invalid.	–

When you finish adding and configuring frame settings, click OK to close the dialog, then click Save changes.

The table describes the available formats:

Format	Description	Minimum Value	Maximum Value	Use "Endian" Setting
INT16	1 register with signed integer value	–32768	32767	No
UINT16	1 register with positive integer value	0	65535	No
INT32	2 registers with signed integer value	–2147483648	2147483647	Yes
UINT32	2 registers with positive integer value	0	4294967295	Yes
FLOAT32	2 registers with signed floating point value coded according to IEEE754 standard	–1E–10	+1E–10	Yes
UINT32_MOD10K	2 registers with positive integer value from 0 to 9999	0	99999999	Yes
INT64	4 registers with signed integer value	–2 (^63)	–2 (^63)–1	Yes
UINT64	4 registers with positive integer value	0	–2 (^63)–1	Yes
UINT64_MOD10K	4 registers with positive integer value from 0 to 9999	0	9 999 999 999 999 999	Yes