Enron Modbus

8 min

Note: If multiple stations are connected to the RS-485 bus, then use the Modbus ASCII Advanced driver instead of this one.

Review the following information for setting up and configuring the Enron Modbus driver.

Litmus Edge Compatible Series

Compatibility parameter	Compatible items
Driver type	Serial (RS-485) or Ethernet
When to use	Serial connection or TCP connection to a Modbus device

To set up and configure this device in Litmus Edge, you will need to do the following:

Step 1: Set up and Configure the PLC Device
Step 2: Set up the PLC Device in Litmus Edge DeviceHub
Step 3: Configure the List of Registers

Step 1: Set up and Configure the PLC Device

If you are setting up an Ethernet connection, find the device's network parameters.
If you are setting up a serial connection, record the serial communication parameters for the device.

Step 2: Set up the PLC Device in Litmus Edge DeviceHub

Configure the following parameters when you Connect a DeviceConnect a Device with this driver. Update default values to the specific setup of your device.

Parameter	Value
Type	Modbus
Driver	Enron Modbus
Override Station ID Override registers' Station ID setting	False True
Override BW Order Override registers' "Bytes And Words Order" setting	False True
Protocol Mode	RTU ASCII
Request Timeout (ms)	2000
Transport Type	Serial TCP/IP
Network Address If TCP/IP selected	The device address you recorded in Step 1.
Network Port If TCP/IP selected	502
Device File If Serial selected	The file of the serial port you are using
Baud Rate If Serial selected	1200 2400 4800 9600 19200 38400 57600 115200 230400 460800 921600
Data Bits If Serial selected	5 6 7 8
Stop Bits If Serial selected	1 1.5 2
Parity If Serial selected	Even Mark None Odd Space

Step 3: Configure the List of Registers

When you Add Tags to the connected device, refer to the following register table and tag parameters.

Refer to the following additional resources:

Register Table

Name	Value Types	Address Format	Min Address	Max Address	Description
1x	bool	1DDD	100	1999	Boolean Registers
3x	int16	3DDD	3001	1999	Short 16-bit Integer Registers
5x	int32	5DDD	5001	1999	Long 32-bit Integer Registers
7x	float32	7DDD	7001	65535	Floating Point Registers
EventAlarm	JSON				Event/Alarm Register
Acknowledgment	bool				Event/Alarm Acknowledgment (write only)
Archive	JSON	7DD	701	799	Hourly and Daily Archive
Str	string	5DDD	5001	5999	String Registers (5x)

Tag Parameters

Name: Select a register name from the drop-down list. The available options depend on the names in the register table.
Value Type: Select a data type from the drop-down list. The available options depend on the register name selected.
Polling Interval: Enter a value in seconds. This determines how often the tag should poll the register for data.
Tag Name: Enter a name for the tag.
Description (Optional): Enter a description for the tag.
Record Number (not available for all names): Enter the record number for the tag.
Address: Enter a tag address. The value must in the decimal format, within the allowed min/max range. Omit the leading zeros. The device might use the decimal (D), hexadecimal (H), or octal (O) address format. See the Register Table at the bottom of the dialog box. For Bit tags, append the bit address without the bit separator. The lowercase letters in the address format indicate how many digits you should enter in the Bit address.
Count: Enter the number of register values to read. A count higher than 1 will generate an array of values from the address value configured and respective subsequent address values.
Station ID: Enter the value that indicates the position of the tag.
Bytes and Words Order (not available for all names): This option configures how the tag data will be formatted and whether bytes and/or words will be counted from the start (big-endian style) or end (little-endian style) of strings of data. Select one of the following options.
- Bytes-BigEndian: Only bytes will be formatted in big-endian style (counted from the start).
- Bytes-LittleEndian: Only bytes will be formatted in little-endian style (counted from the end).
- Bytes-BigEndian, Words-BigEndian: Both bytes and words will be formatted in big-endian style (bytes and words counted from the start). For example: AB CD.
- Bytes-BigEndian, Words-LittleEndian: Bytes will be formatted in big-endian style and words will be formatted in little-endian style. For example: CD AB.
- Bytes-LittleEndian, Words-BigEndian: Bytes will be formatted in little-endian style and words will be formatted in big-endian style. For example: BA DC.
- Bytes-LittleEndian, Words-LittleEndian: Both words and bytes will be formatted in little-endian style (counted from the end). For example: DC BA.
Tag Formula: Enter a formula for the tag to process the generated data. Two variables are permitted: value (current tag value) and timestamp (current tag UNIX time in milliseconds). The following math functions are available:
- sin
- cos
- sqrt
- tan
- power: power(x) performs the operation 10^x.
- log: log(x) is the natural logarithm (the logarithm is in base e).
- exp: exp(x) performs the operation e^x.
Only Publish on Change of Value: Select the checkbox to customize NATS messages to be published only when the value parameter changes from a previous value to a new one. Change of Value only applies to boolean, numeric (such as int or float), and simple string data types. It does not apply to complex types, such as JSON or array. Poll-once topics will not be affected by Change of Value settings. These topics will still only see a single message.
Meta Data: Metadata summarizes basic information about data. This feature allows you to define key-value pair data for the device output payload later on. It can then be used to find, use, and reuse particular instances of data.

Note: If you use special characters in meta data key names, the special characters are replaced with underscore characters in the payload. This can cause two key names to be combined into one. For example, configuring the key names a**b and a&&b will cause only one key name to be created (a__b).