EtherNet/IP

EtherNet/IP (Ethernet Industrial Protocol) is an industrial communication protocol based on CIP (Common Industrial Protocol). It is managed by ODVA (Open DeviceNet Vendors Association). It runs over TCP/IP and UDP, using port 44818 by default.

inSCADA supports the EtherNet/IP protocol in Client role only.

Supported Devices

inSCADA’s EtherNet/IP implementation uses tag-based addressing (CIP implicit messaging). This addressing method is supported on the following control platforms:

Platform	Support	Description
ControlLogix (Allen-Bradley)	✓	Logix 5000+ series — full support
CompactLogix (Allen-Bradley)	✓	Logix 5000+ series — full support
SoftLogix (Rockwell)	✓	PC-based Logix runtime environment
MicroLogix (Allen-Bradley)	✗	Data file-based addressing — not supported
SLC 500 (Allen-Bradley)	✗	Data file-based addressing — not supported
PLC-5 (Allen-Bradley)	✗	Data file-based addressing — not supported

Note

Why is MicroLogix/SLC/PLC-5 not supported?

These older platforms use data file-based addressing (e.g., N7:0, F8:3, B3/0). inSCADA’s EtherNet/IP implementation uses the tag-based addressing structure of the Logix 5000+ series (e.g., Motor_1_Speed, Tank.Level). These two addressing methods differ at the protocol level — the CIP message structure and routing mechanism are incompatible.

If communication with data file-based devices is required, an OPC DA/UA gateway or a proxy through ControlLogix can be used as alternatives.

Tag-Based Addressing

On Logix platforms, data is accessed by tag (label) names. Instead of register addresses, the tag name defined in the program is used directly:

Motor_1_Speed          → Simple tag (REAL)
Tank.Level             → UDT (User Defined Type) member
Station[3].Temp        → Array element
Program:MainProgram.Counter  → Program scope tag

This approach:

• Is human-readable — the tag name describes what the data is
• Maps directly to the PLC program
• Eliminates the need for register address calculations

Data Model

Connection (IP, port, timeout)
└── Device (Slot number)
    └── Frame (Data Block — Grouping)
        └── Variable (Tag name)

Configuration

Connection

Parameter	Example	Description
Protocol	EthernetIp	Protocol selection
IP Address	192.168.1.1	PLC IP address
Port	44818	EtherNet/IP port (default: 44818)
Timeout	5000 ms	Request timeout duration
Retries	3	Number of failed request retries

Device

Parameter	Example	Description
Slot	0	PLC backplane slot number
Scan Time	1000 ms	Scan period
Scan Type	PERIODIC	PERIODIC or FIXED_DELAY

Tip

Slot number is the physical position of the PLC CPU module on the chassis. For CompactLogix it is typically 0, for ControlLogix it is the slot where the CPU is installed (e.g., 0, 1, or 2).

Frame

In EtherNet/IP, a Frame is used only to group variables. There are no protocol-specific additional parameters.

Variable

Parameter	Example	Description
Name	Motor_1_Speed	Tag name in the PLC (full path)
Type	REAL	CIP data type
Bit Parent Type	(optional)	Parent data type for bit access

The variable name must be exactly the same as the tag name in the PLC program. inSCADA uses this name to send a CIP Read/Write Tag Service request.

Supported Data Types

Data Type	CIP Size	Description
BIT	1 bit	Single bit (requires Bit Parent Type)
BOOL	1 bit	Boolean value
SINT	8 bit	Signed 8-bit integer (-128 ~ 127)
INT	16 bit	Signed 16-bit integer (-32768 ~ 32767)
DINT	32 bit	Signed 32-bit integer
LINT	64 bit	Signed 64-bit integer
REAL	32 bit	32-bit floating point (IEEE 754)
BITS	32 bit	Bit array (as 32-bit word)
STRUCT	Variable	Structured data type (UDT)

Bit Access

The BIT type is used to access a single bit. In this case, the Bit Parent Type must be selected to specify which data type the bit is read from:

Bit Parent Type	Description
SINT	Read bit from 8-bit integer
BITS	Read bit from 32-bit word

Tag Name Examples

Tag Name	Type	Description
Motor_Speed	REAL	Simple controller tag
Tank.Level	REAL	UDT (structured type) member
Sensors[0]	DINT	First element of array
Sensors[5]	DINT	6th element of array
Station[2].Temperature	REAL	Array + structured type
Program:MainProgram.LocalTag	INT	Program scope tag
Motor_Run	BOOL	Boolean tag
StatusBits	BITS	32-bit status word

Batch Read

inSCADA reads EtherNet/IP tags in bulk for performance. Multiple tags are read with a single CIP request:

• Normal tags: 20 tags/request
• String tags: 5 tags/request (larger payload)
• Bit tags: 20 tags/request (read via parent type)

This behavior is automatic — no user configuration is required.

Rockwell Studio 5000 / RSLogix 5000 Notes

No special configuration is required on the PLC side for communication with inSCADA. The following points should be checked:

• Ensure tags are defined as Controller Scope (global) — for Program scope tags, use the Program:ProgramName.TagName format
• Verify that the PLC’s Remote Access settings are enabled
• Ensure port 44818 is open in the firewall