Why Omron has two distinct protocol families
Omron's communication protocol history divides cleanly at the NJ/NX generation. Every Omron PLC from the legacy C-series through the CJ2 and CS1 families communicates using FINS — Factory Interface Network Service — a proprietary Omron protocol that runs over both Ethernet (UDP/IP) and serial transports. The NJ and NX Machine Automation Controllers, introduced with the Sysmac platform, use EtherNet/IP and the Common Industrial Protocol (CIP) — the same standard as Rockwell Automation's ControlLogix — and use symbolic tag-based addressing instead of FINS memory type addressing. Understanding which side of this divide your hardware sits on determines which driver you need.
Beyond these two primary protocol families, older Omron PLCs used the Host Link serial protocol (the predecessor to FINS), specialist equipment used Toolbus, and the E5-series temperature controllers use the Process Suite serial protocol. The TOP Server Omron Communications Suite covers all six of these protocol paths in a single license.
Sysmac and the NJ/NX platform: Omron's Sysmac platform — introduced around 2012 — represents a fundamental architecture shift. NJ and NX controllers are programmed in IEC 61131-3 using Sysmac Studio (not CX-Programmer), use tag-based symbolic addressing, and communicate via EtherNet/IP/CIP rather than FINS. If your Omron hardware was purchased and installed after roughly 2012 and is branded as a "Machine Automation Controller," it is almost certainly NJ or NX and requires the NJ/NX Ethernet driver, not the FINS drivers.
The major Omron protocols at a glance
Omron protocols break into three eras: the legacy serial protocols (Host Link, Toolbus), the classic FINS era covering the majority of the installed base (C-series through CJ/CS/CP), and the modern Sysmac era (NJ/NX via EtherNet/IP). The E5 temperature controllers use their own dedicated serial protocol regardless of generation.
EtherNet/IPEtherNet/IP / CIP
The current protocol for NJ and NX Machine Automation Controllers
The NJ and NX families communicate via EtherNet/IP — the same CIP-based protocol used by Rockwell Automation's ControlLogix. TOP Server connects directly without requiring Omron's CX-Compolet middleware. Data is accessed by symbolic tag name. Supports all basic data types including BOOL, SINT/USINT, INT/UINT, DINT/UDINT, LINT/ULINT, REAL, LREAL, and String. CIP routing enables single- and multi-hop access to remote controllers.
Used by: NJ301, NJ501, NX series (all), CJ1W-EIP21, any Omron controller with EtherNet/IP support
FINS / EthernetFINS over Ethernet (UDP/IP)
High-speed Ethernet access to C, CV, CJ, CS, and CP families
FINS (Factory Interface Network Service) is Omron's proprietary application-layer protocol. Over Ethernet, FINS uses UDP/IP (not TCP) — source and destination port numbers must match (default 9600). FINS uses typed memory area addressing: CIO, D, W, H, A, T/C, E, and others. Supports FINS Gateway for routing through Sysmac Link and Sysmac Net.
Used by: CJ1, CJ2, CS1, CP series (CP1E/CP1H/CP1L), CVM1, C200, C500–C2000, CV500–CV2000
FINS / SerialFINS over Serial (RS-232/RS-422)
Serial FINS for controllers without Ethernet connectivity
The FINS protocol also runs over serial connections via the controller's programming/peripheral port or a dedicated serial communications board. Uses the same memory area addressing as FINS Ethernet. Supports Ethernet Encapsulation via serial-to-Ethernet converters.
Used by: CJ1, CJ2, CS1, CVM1, CV500–CV2000, C200, C500, C1000, C2000
SerialHost Link (C-mode)
The original Omron serial protocol — C-series and classic controllers
Host Link (SYSMAC WAY) is Omron's original serial communication protocol, predating FINS. It operates over RS-232 or RS-422 at up to 19.2 kbps in a master-slave configuration. Uses memory areas by type (IR, SR, AR, DM, HR, TC, LR). An OPEN model option covers the broadest range of non-model-specific addressing.
Used by: C1000, C200, C200H, C20H, C500, CQM1, QM1, CV series; also OPEN mode for any Host Link-compatible device
Process / SerialProcess Suite (E5 Temperature Controllers)
Dedicated serial protocol for Omron E5-series temperature controllers
Omron's E5-series temperature controllers use a dedicated serial protocol distinct from FINS or Host Link. Connects via RS-485 (multi-drop) or RS-232 for single-device connections. Supports both RTD and thermocouple input types; reads setpoints, process values, and alarm states.
Used by: E5AF-A/AH, E5AJ-A, E5AX-A/AH/DAA/PRR/VAA, E5CN (RTD and thermocouple), E5EJ-A, E5GN (RTD and thermocouple)
Toolbus / SerialToolbus
Specialist Omron serial protocol for CJ1 and CS1 via peripheral port
Toolbus is a specialized Omron serial protocol used to access CJ1 and CS1 controllers via the CPU's peripheral (tool) port — the same port used by CX-Programmer. Provides direct CPU memory access at higher speed than Host Link.
Used by: CJ1G, CJ1G-H, CJ1H-H, CJ1M; CS1-G, CS1-H (via peripheral/tool port)
FINS memory addressing vs. EtherNet/IP symbolic addressing
The most practically important difference between connecting to a classic Omron controller (CJ, CS, CP, C-series) and a Sysmac controller (NJ, NX) is the addressing model. FINS uses typed memory area addressing with numeric word and bit offsets; EtherNet/IP uses symbolic tag names defined in Sysmac Studio.
FINS memory area addressing (CJ, CS, CP, C-series)
Classic Omron controllers organize data into named memory areas, each with a type prefix and a numeric word/bit address. Data is accessed by specifying the area and offset — CIO 0.00 for the first input bit, D100 for data memory word 100, and so on. This is the addressing format used by the FINS Ethernet and FINS Serial drivers.
Symbolic tag addressing (NJ, NX)
Sysmac Studio-programmed NJ and NX controllers assign every variable a symbolic name. Instead of D100, you access ConveyorSpeed_RPM. The NJ/NX Ethernet driver performs automatic tag generation by connecting to the controller and reading the full tag database, populating the TOP Server tag browser with the controller's named variables — no manual address entry required.
FINS — Memory Area Addressing (CJ/CS/CP)
CIO 0.00CIO bit 0 word 0
D100Data memory word 100
W200Work area word 200
H50Holding relay word 50
T10.PVTimer 10 present value
A200Auxiliary area word 200
EtherNet/IP — Symbolic Tags (NJ/NX)
ConveyorSpeed_RPMDINT
ReactorTemp_degCREAL
MotorRunningBOOL
BatchData.TotalUnitsUDINT struct
TempArray[0]REAL array element
AlarmStatus.HighTempBOOL struct member
FINS memory area reference
The FINS Ethernet and FINS Serial drivers access controller data using Omron's memory area designators. Understanding these areas is essential for configuring FINS-based tags in TOP Server.
| Designator | Memory Area | Description | Read/Write |
|---|
| CIO | Core I/O (Channel I/O) | The primary I/O area. Includes physical I/O bits and internal relay bits used for logic. | R/W |
| D | Data Memory (DM) | General-purpose data registers. The most commonly used area for process variables and recipe data. | R/W |
| W | Work Area | Temporary work registers used in program execution. Not battery-backed on most models. | R/W |
| H | Holding Relay (HR) | Battery-backed data area. Retains values through power cycles. Used for setpoints and persistent state. | R/W |
| A | Auxiliary Area (AR) | System flags and status bits. Many bits are read-only (controller status, error flags). Some are writable. | R/(partial W) |
| T | Timer Area | Timer completion flags (T) and present values (TS). Writing to TS requires Monitor Mode. | R/W* |
| C | Counter Area | Counter completion flags (C) and present values (CS). Writing to CS requires Monitor Mode. | R/W* |
| E | Extended Data Memory (EM) | Extended DM banks (E0–EC) available on controllers with expanded memory. Bank selection required. | R/W |
| DR | Data Register | Index registers for indirect addressing. Writes only supported in Programming Mode. | R/W† |
| IR | Index Register | Index registers for indirect addressing. Writes only supported in Programming Mode. | R/W† |
* Writes to T (TS) and C (CS) addresses while the controller is in Run Mode require special handling. † DR and IR register writes are only supported in Programming Mode.
Protocol comparison
The table below summarizes the key characteristics of each Omron protocol to help engineers identify the right connectivity path for their hardware.
| Protocol | Transport | Addressing | Routing support | Auto tag gen | Status |
|---|
EtherNet/IP (CIP) | TCP/IP Ethernet | Symbolic tag names | CIP multi-hop routing | Yes — live from controller | Current — NJ/NX |
FINS Ethernet | UDP/IP (port 9600) | Memory area (CIO, D, W…) | FINS Gateway / Sysmac Net | Manual tag entry | Current — CJ/CS/CP |
FINS Serial | RS-232 / RS-422 | Memory area (CIO, D, W…) | No | Manual tag entry | Legacy/current — CJ/CS/CV/C |
Host Link (C-mode) | RS-232 / RS-422 | Memory area (IR, DM, HR…) | No | Manual tag entry | Legacy — C/CQM1/CV series |
Process Suite Serial | RS-232 / RS-485 | Parameter registers | No | Manual tag entry | Current — E5 temperature ctrl |
Toolbus Serial | RS-232 (peripheral port) | Memory area (CIO, D, W…) | No | Manual tag entry | Legacy — CJ1/CS1 only |
Which protocol does my Omron controller use?
Use the matrix below to identify which communication protocols are available for your controller family and which TOP Server driver covers each path.
| Controller Family | NJ/NX Eth (EIP) | FINS Eth | FINS Ser | Host Link | Toolbus | Process Suite |
|---|
| NJ Series (NJ301/501) | ✓ | – | – | – | – | – |
| NX Series | ✓ | – | – | – | – | – |
| CJ2 Series | Via EIP module | ✓ | ✓ | – | – | – |
| CJ1 Series | Via CJ1W-EIP21 | ✓ | ✓ | – | ✓ | – |
| CS1 Series | – | ✓ | ✓ | – | ✓ | – |
| CP Series (CP1E/H/L) | – | ✓ | – | – | – | – |
| CVM1 Series | – | ✓ | ✓ | – | – | – |
| CV Series (CV500–CV2000) | – | ✓ | ✓ | ✓ | – | – |
| C Series (C200–C2000) | – | ✓ | ✓ | ✓ | – | – |
| CQM1 / QM1 | – | – | – | ✓ | – | – |
| E5 Temperature Controllers | – | – | – | – | – | ✓ |
✓ = Native support | Via = requires specific EtherNet/IP communication module | – = not supported
How TOP Server connects to Omron controllers
The TOP Server Omron Communications Suite bundles all six drivers in a single license. No third-party software — including Omron's own CX-Compolet middleware — is required. Here is what each driver does and the specific hardware and protocol it covers.
NJ / NX Ethernet
Omron NJ / NX Ethernet Driver
The primary driver for Omron's Sysmac platform. Connects to NJ and NX Machine Automation Controllers via EtherNet/IP using CIP explicit messaging — no CX-Compolet required. Performs Online Automatic Tag Generation directly from the controller. Supports all standard IEC data types. CIP routing allows single- and multi-hop communication to reach remote controllers.
Covers: NJ301, NJ501, NX1 and all NX series, CJ1W-EIP21, any Omron controller with EtherNet/IP support
FINS Ethernet
Omron FINS Ethernet Driver
Connects to FINS-compatible Omron PLCs over Ethernet using the FINS/UDP protocol. FINS requires the source and destination port numbers to match (default 9600). Supports all FINS memory areas: A, CIO, C, CS, D, DR, E, H, IR, TK, T, TS, W. FINS Gateway support allows routing through Sysmac Link and Sysmac Net.
Covers: CJ1, CJ2, CS1, CP1E/CP1H/CP1L, CVM1, C200/C500/C1000/C2000, CV500/CV1000/CV2000
FINS Serial
Omron FINS Serial Driver
Connects to Omron controllers via serial RS-232 or RS-422 using the FINS serial protocol. Uses the same memory area addressing model as FINS Ethernet. Supports Ethernet Encapsulation via serial-to-Ethernet converter hardware.
Covers: CJ1, CJ2, CS1, CVM1, CV500/CV1000/CV2000, C200/C500/C1000/C2000
Host Link Serial
Omron Host Link Serial Driver
Connects to classic Omron controllers using the Host Link (C-mode/SYSMAC WAY) serial protocol. Memory areas use classic Omron notation: CIO, SR, HR, AR, DM, LR, TC. An OPEN model option provides the broadest possible address space for non-specific devices.
Covers: C1000, C200, C200H, C20H, C500, CQM1, QM1, CV series; OPEN mode for any Host Link-compatible device
Process Suite Serial
Omron Process Suite Serial Driver
Connects to Omron E5-series temperature and process controllers via RS-232 (single device) or RS-485 (multi-drop, up to 31 devices per bus). Supports both platinum RTD and thermocouple sensor input types. Reads and writes setpoints, process values, alarm status, and control parameters.
Covers: E5AF-A/AH, E5AJ-A, E5AX-A/AH/DAA/PRR/VAA, E5CN (RTD and thermocouple), E5EJ-A, E5GN (RTD and thermocouple)
Toolbus Serial
Omron Toolbus Serial Driver
Connects to CJ1 and CS1 controllers via the CPU's peripheral (tool) port using the Toolbus protocol — the same interface used by CX-Programmer. Provides higher-speed serial access than Host Link with access to the full CJ/CS memory area set.
Covers: CJ1G, CJ1G-H, CJ1H-H, CJ1M; CS1-G, CS1-H (peripheral/tool port connection only)
Ethernet Encapsulation for serial drivers: The FINS Serial, Host Link Serial, Process Suite Serial, and Toolbus Serial drivers all support Ethernet Encapsulation. A serial-to-Ethernet converter (Moxa NPort, Digi, or similar) at the controller bridges the serial protocol over TCP/IP. TOP Server connects to the converter's IP address and port. This is the recommended approach for modernizing serial-connected Omron installations.
Frequently asked questions
Why does FINS use UDP instead of TCP, and does that cause reliability problems?+−
FINS was designed to operate over Omron's proprietary Sysmac Net and Sysmac Link networks before Ethernet was common. When Omron adapted FINS for Ethernet, they mapped it to UDP/IP because UDP's connectionless design matched FINS's own command/response model.
In practice, FINS over UDP works reliably on a well-managed plant network. Problems arise when FINS traffic traverses routers or firewalls that treat UDP differently than TCP. An important note: FINS requires the source port number on the TOP Server machine and the destination port on the device to match (default 9600). If CX-Programmer is using the same port, conflicts can occur.
Does the NJ/NX Ethernet driver require Omron's CX-Compolet software?+−
No. TOP Server's NJ/NX Ethernet driver communicates directly with the NJ/NX controller using EtherNet/IP and CIP without any Omron middleware. CX-Compolet is not required, reducing the software stack, licensing cost, and support complexity.
How does CIP routing work for reaching remote Omron NJ controllers?+−
CIP routing allows TOP Server to use a local NJ controller as a gateway to reach NJ, NX, or CJ1 controllers on other network segments without needing a direct Ethernet connection to each remote controller. This is configured in the Device ID field using a path syntax that specifies the local gateway IP address, the backplane port, and the CPU unit address.
What are the CP series special requirements for FINS Ethernet connectivity?+−
The CP series (CP1E, CP1H, CP1L) supports FINS Ethernet, but requires specific configuration in the controller before TOP Server can connect. The required Omron FINS Ethernet module settings must be configured in CX-Programmer before the FINS Ethernet driver will establish a connection. If you are having trouble connecting to a CP series device, the controller-side FINS settings are almost always the cause.
Can I read and write to Omron temperature controllers (E5 series) from the same OPC connection that reaches my PLCs?+−
Yes. A single TOP Server instance with the Omron Suite license can simultaneously connect to CJ2 PLCs via FINS Ethernet, NJ controllers via EtherNet/IP, and E5-series temperature controllers via the Process Suite Serial driver, all serving data to OPC clients through a unified tag namespace.
Does the Omron Communications Suite include all six drivers in one license?+−
Yes. The TOP Server Omron Communications Suite is a single perpetual license that includes all six drivers: NJ/NX Ethernet, FINS Ethernet, FINS Serial, Host Link Serial, Process Suite Serial, and Toolbus Serial. All drivers can be active simultaneously on the licensed machine. Individual drivers are also available as standalone licenses. Contact Software Toolbox to confirm the most appropriate licensing for your device mix.
Ready to connect your Omron controllers?
TOP Server's Omron Suite covers every Omron PLC generation — from legacy C-series through modern NJ/NX — with no third-party middleware required. Try it free or talk to an engineer.
