Connecting Modbus sensors using "RS485 to USB adapter"

1

Name

Created element name

2

User-defined type

Defines the icon to be displayed in the "System tree"

3

Units of measurement

The unit of measure in which the value is displayed in the "System tree"

4

Minimum value

Determines the minimum measurement range, when the value is out of range, the sensor goes into the "Not connected" state

5

Maximum value

Determines the maximum measurement range, when the value is out of range, the sensor goes into a "Not connected" state

6

Alarm and warning levels

Defines the alarm and warning thresholds, as for other sensors, see Sensor configuration

7

Hysteresis

Option of setting the hysteresis state, see Sensor configuration

8

Expression

Function of the form f (x). The default value for the sensor is equal to the measured value: "x", ie corresponds to the expression "x". To calculate the indirect value of the sensor is possible to use an arbitrary expression, which is permissible "(", ")", as well as:

• • operators: "+", "-", "*", "/", "%" (remainder of the division), "^" (exponentiation);

  • functions: "abs","sqrt","exp","ln","log","sin","cos","tan","asin","acos","atan";

  • constants: "pi" (3.1415926...), "e" (2.7182818...);

  • point is used as a decimal separator (3.14).

        For example: "0.1*x+0.5"

1

Slave address

Modbus RTU slave address of external equipment

2

Register index

Modbus protocol register start address in hexadecimal view, like 0F4A

3

Function code

The following functions are supported:

• 0x01 - Read Coil Status

• 0x02 - Read Input Status

• 0x03 - Read Holding Register

• 0x04 - Read Input Register

4

Data type

Determines how to present the data:

• 16 bits signed int

• 16 bits unsigned int

• 32 bits signed int

• 32 bits unsigned int

• 32 bits IEEE floating point

5

Data ordering

Determines byte order in Modbus protocol response message:

• low byte first, low word first

• low byte first, high word first

• high byte first, low word first

• high byte first, high word first

6

Polling period

Defines the time of polling the sensor value. From 10 seconds to 5 minutes. 

1

Name

Created element name

2

Slave address

Modbus RTU slave address of external equipment

3

Register index

Modbus protocol register start address in hexadecimal view, like 0F4A

4

Function code

The following functions are supported:

• 0x05 - Write Single Coil

• 0x06 - Write Single Register

5

Writing value

Decimal integer value that will be written in the specified register