AB ControlLogix Unsolicited

7 min

Review the following information for setting up and configuring the AB ControlLogix Unsolicited driver. The driver receives data that a ControlLogix or CompactLogix PLC sends to Litmus Edge over EtherNet/IP (CIP).

Unlike most drivers, this driver does not poll the PLC. It listens on a TCP port and accepts connections from the PLC. The PLC sends data with CIP Data Table Write MSG instructions. Each tag returns the last value that the PLC sent for that tag name.

Note: This driver is experimental. Some features might not work as expected.

Litmus Edge compatible series

Compatibility parameter	Compatible items
Driver type	Ethernet
Validated devices/series	ControlLogix and CompactLogix controllers that support the CIP Data Table Read/Write MSG instruction

To set up and configure this device in Litmus Edge (LE), 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

Make sure the PLC can reach the LE device over the network, and record the IP address of the LE network interface that the PLC connects to.

In the PLC program, configure a MSG instruction for each value that you want to send to LE:

Message type: CIP Data Table Write

Destination element: The tag name that you enter for the tag in LE. Tag names are case-sensitive.

Path: The IP address of LE. The driver listens on port 44818 by default.

The PLC sends a value each time the MSG instruction runs. To send values regularly, trigger the instruction from a timer in the PLC program.

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	Allen-Bradley
Driver	AB ControlLogix Unsolicited
NetworkInterface	The LE network interface (IP address) that the driver listens on. Default value 0.0.0.0, which listens on all interfaces
NetworkPort	The local TCP port that the driver listens on for connections from the PLC. Enter a value from 0 to 65535. Default value 44818

The following parameter is under Advanced Parameters.

Parameter	Value
ReadTimeout	How long a PLC connection can stay silent, in milliseconds. If the PLC sends nothing for this long, the driver drops the connection and sets the connection's tags to down. Enter a value from 1000 to 999999. Default value 10000

For the Meta Data, Status Register, and Optional Settings options, see Connect a DeviceConnect a Device.

Step 3: Configure the list of registers

When you Add a TagAdd a Tag to the connected device, see the following sections. This driver does not support browsing tags.

See the following additional resources if necessary:

Organize Device and Tag Data by Using MetadataOrganize Device and Tag Data by Using Metadata

Tag Formula VariablesTag Formula Variables

Free tags

This driver doesn't have a list of register names in the DeviceHub Add Tag form. In the Name field, enter the CIP tag name that the PLC sends, exactly as the MSG instruction defines it. Tag names are case-sensitive.

The tag updates each time the PLC sends a value for that tag name. The device doesn't show a Connected status until the PLC connects and sends data for a configured tag.

Available value types

bool

sint

dint

real

lint

Tag parameters

Name: Enter the CIP tag name that the PLC sends. See the Free tags section.

Value Type: Select a data type from the drop-down list.

ClientIP (Optional): Enter the IP address of a PLC. If you enter an address, only values sent from that PLC update the tag, and the tag goes down when that PLC disconnects. Use this setting when several PLCs send the same tag name and you want a separate tag for each PLC.

Tag Name: Enter a name for the tag.

Description (Optional): Enter a description for the tag.

Tag Formula: Enter a formula for the tag to process the generated data. You can use two variables: value (current tag value) and timestamp (current tag UNIX time in milliseconds). The following math functions are available:

sqrt

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 publish NATS messages only when the value parameter changes. 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 are not affected by Change of Value settings, and still receive a single message.

Meta Data: Define key-value pairs to add to the device output payload.

Note: If you use special characters in metadata 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 creates only one key name (a__b).