Yokogawa connectivity: what makes it different
Unlike PLC manufacturers whose connectivity challenge is primarily about control system protocols, Yokogawa's connectivity challenge is about data acquisition. Yokogawa devices — chart recorders, paperless recorders, data loggers, and loop controllers — are primarily measurement instruments. They capture high-fidelity process data: channel values, engineering units, alarm states, channel configuration, and timestamps. Getting that data into OPC-based systems for historians, SCADA, and analytics requires device-specific drivers because each Yokogawa product family uses its own proprietary data acquisition protocol.
Yokogawa's instrumentation product lines span multiple generations. The DX series paperless recorders and the Darwin series represent earlier platforms; SMARTDAC+ (GX/GP/GM series) is Yokogawa's current flagship recorder and data acquisition platform; MX100 and MW100 are modular data acquisition systems; and the Green Series (UT/UP controllers) are compact loop controllers widely used in temperature and process control. Each of these has a distinct communication protocol and requires a dedicated TOP Server driver.
Data recorders vs. PLCs: Yokogawa devices are primarily instrumentation and data acquisition products rather than general-purpose programmable controllers. Their protocols are optimized for reading channel data, alarm states, and device configuration — not for executing ladder logic or managing I/O racks the way a PLC does. This means Yokogawa connectivity is often about bringing high-quality process measurement data into OPC for trending, compliance recording, and analytics, rather than control system integration.
The Yokogawa device families and their protocols
Each Yokogawa product family uses a purpose-built data acquisition protocol. The protocol name, transport options, and the data accessible through that protocol differ across families. Here is a reference overview of each.
Recorder / DAQDX Series
Paperless chart recorders — DX100/200 and MV100/200 families
The DX series are Yokogawa's mid-range paperless recorders. They communicate using the Yokogawa DX Data Acquisition Protocol over both Ethernet (TCP/IP) and serial (RS-232/RS-422). Available data includes channel process values, alarm status, channel configuration, and date/time. The Ethernet variant supports up to 1,024 devices per channel and includes the AS1 Advanced Security Option for access control.
Models: DX102, DX104, DX106, DX112, DX204, DX208, DX210, DX220, DX230, DX1002, DX1004, DX1006, DX1012, DX2004–DX2048; MV100, MV200
SMARTDAC+GX / GP / GM Series
Yokogawa's current-generation SMARTDAC+ platform
The GX, GP, and GM series are Yokogawa's current SMARTDAC+ data acquisition and recording platform. They use the Yokogawa GX/GP/GM Data Acquisition Protocol over Ethernet TCP/IP. The GX driver in TOP Server provides read access to process values, alarm states, and channel configuration from I/O, math, and communications channels. Write operations are not currently supported via this protocol interface.
Models: GX10, GX20 (data recorders); GP10, GP20 (data recorders with display); GM10 (modular data acquisition system)
Modular DAQMX100
High-channel-count modular data acquisition — up to 1,080 channels
The MX100 is Yokogawa's high-density modular data acquisition system, capable of scaling to over 1,000 channels in a single system. It uses the Yokogawa MX Data Acquisition Protocol over Ethernet TCP/IP. TOP Server's MX Ethernet driver provides access to channel data, alarm states, and device status. The Stop MX on Shutdown feature optionally commands the MX100 to stop measurement activity when TOP Server shuts down.
Models: MX100 (all sub-models and channel expansion units)
Modular DAQMW100
Web-enabled distributed data acquisition system
The MW100 is Yokogawa's web-enabled distributed data acquisition module. It is designed for remote, distributed measurement applications and communicates over Ethernet TCP/IP using the Yokogawa MW Data Acquisition Protocol. The MW100 can operate as a standalone data logger with local storage and a built-in web interface, making it common in applications where measurements need to be accessible both locally and from a central OPC infrastructure.
Models: MW100 (all configurations and optional expansion modules including AX100)
RecorderDarwin Series
Compact hybrid recorders — Ethernet and serial variants
The Darwin series are Yokogawa's compact hybrid recorders that combine pen-and-ink and digital recording capabilities. They communicate using the Yokogawa Darwin Data Acquisition Protocol over both Ethernet (TCP/IP) and serial (RS-232/RS-422). Darwin devices are common in older installations, particularly in the pharmaceutical industry where their hybrid paper/digital recording satisfied both modern data capture and legacy paper trail requirements.
Models: DR131, DR231, DR232, DR241, DR242; DA100-1, DA100-2, DC100-1, DC100-2
RecorderDXP Series
Paperless recorders with enhanced data processing
The DXP series are Yokogawa paperless recorders with built-in data processing capabilities, sitting above the base DX series in functional capability. The DXP100 and DXP200 use the Yokogawa DXP Data Acquisition Protocol over Ethernet TCP/IP — a distinct protocol from the standard DX series that reflects the additional data structures and measurement capabilities of the DXP hardware.
Models: DXP100, DXP200
ControllerCX Series
Paperless recorder controllers — CX1000/2000
The CX series combines data recording and loop control in a single instrument. The CX1000 and CX2000 are hybrid controller-recorders widely used in batch processing and temperature control applications. They communicate using the Yokogawa CX Data Acquisition Protocol over Ethernet TCP/IP. The CX Ethernet driver in TOP Server provides access to process values, setpoints, and alarm states from these combined recorder-controller instruments.
Models: CX1000, CX2000
Serial / PCLinkGreen Series Controllers
Compact loop controllers via PCLink and RS-422
Yokogawa's Green Series (UT and UP controllers) are compact, panel-mount loop controllers used extensively in temperature and process control applications across virtually every process industry. They communicate primarily via PCLink — Yokogawa's serial multi-drop communication protocol for controller networks — over RS-422 (4-wire). Early models (UT37, UT38, UP27) communicate directly via RS-422 at up to 4800 baud.
Models: UT37, UT38, UP27; PCLink: UT130/150/152/155, UT320/350/351/420/450/520/550/750, UP150/350/550/750, US1000
Legacy RecorderHR2400 Series
Hybrid chart recorders — 10, 20, and 30 channel variants
The HR2400 is an older Yokogawa hybrid chart recorder that uses a serial communication protocol distinct from the more modern DX and Darwin families. It communicates via RS-232 serial using the HR2400 serial protocol and is available in 10-channel, 20-channel, and 30-channel configurations. Many plants in regulated industries have HR2400 units still in operation.
Models: HR2400 (10-channel), HR2400 (20-channel), HR2400 (30-channel)
What data is accessible from Yokogawa devices via OPC
A distinguishing characteristic of Yokogawa device protocols is that they expose significantly more than raw channel values. The data accessible through TOP Server's Yokogawa drivers reflects the full measurement and configuration context of each instrument, making it valuable for both real-time monitoring and audit trail applications.
The categories of data accessible vary by device family and driver, but across the suite the following data types are commonly available:
Process values per channel, real-time
Alarm status high/low/rate alarms
Channel configuration tag name, range, EU
Math channel values computed channels
Communications channels external data channels
Device clock / timestamp with sync option
I/O channel data physical inputs
Error / out-of-range flags +INF / –INF / status
Setpoints CX series controllers
Control outputs CX series controllers
Read vs. read/write: Most Yokogawa data acquisition devices are primarily measurement instruments — their protocols are optimized for data readout rather than two-way control. The GX/GP/GM SMARTDAC+ family, for example, supports reads of process values, alarms, and channel configuration but does not currently support writes via the Yokogawa GX protocol. The CX series controller-recorders and the Green Series loop controllers support both reads and writes, allowing setpoint changes and other control parameters to be pushed from an OPC client.
Protocol comparison
The table below summarizes the communication characteristics of each Yokogawa device family's protocol to help engineers plan their connectivity architecture.
| Device Family | Protocol | Transport | Ethernet | Serial | Security | Write support |
|---|
DX100/200, MV100/200 | Yokogawa DX Protocol | TCP/IP or RS-232/422 | Yes | Yes | AS1, user/password | Limited (clock sync) |
SMARTDAC+ GX/GP/GM | Yokogawa GX Protocol | TCP/IP Ethernet | Yes | No | AS1, user/password | Read only |
MX100 | Yokogawa MX Protocol | TCP/IP Ethernet | Yes | No | User/password | Limited (stop/start) |
MW100, AX100 | Yokogawa MW Protocol | TCP/IP Ethernet | Yes | No | User/password | Limited |
Darwin DR/DA/DC | Yokogawa Darwin Protocol | TCP/IP or RS-232/422 | Yes | Yes | Standard | Limited (clock sync) |
DXP100/200 | Yokogawa DXP Protocol | TCP/IP Ethernet | Yes | No | AS1, user/password | Limited |
CX1000/2000 | Yokogawa CX Protocol | TCP/IP Ethernet | Yes | No | AS1, user/password | Yes (setpoints, config) |
Green Series UT/UP | PCLink / RS-422 direct | RS-422 serial (or encap.) | Via encapsulation | Yes | Standard | Yes (setpoints, config) |
HR2400 | HR2400 Serial Protocol | RS-232 serial | No | Yes | Standard | Read only |
Which driver covers my Yokogawa device?
The TOP Server Yokogawa Suite includes 11 drivers. The matrix below maps each device family to its corresponding driver(s). Some families have both Ethernet and serial drivers — the correct choice depends on which interface is available on the device and how it is connected to the network.
| Device / Family | DX Eth | GX Eth | MX Eth | MW Eth | CX Eth | Dar. Eth | DXP Eth | Grn Ser | Dar. Ser | DX Ser | HR2400 |
|---|
| DX100/200, MV100/200 | ✓ | – | – | – | – | – | – | – | – | ✓ | – |
| SMARTDAC+ GX/GP/GM | – | ✓ | – | – | – | – | – | – | – | – | – |
| MX100 | – | – | ✓ | – | – | – | – | – | – | – | – |
| MW100 / AX100 | – | – | – | ✓ | – | – | – | – | – | – | – |
| CX1000 / CX2000 | – | – | – | – | ✓ | – | – | – | – | – | – |
| Darwin DR/DA/DC series | – | – | – | – | – | ✓ | – | – | ✓ | – | – |
| DXP100 / DXP200 | – | – | – | – | – | – | ✓ | – | – | – | – |
| Green Series UT37/38, UP27 | – | – | – | – | – | – | – | ✓ | – | – | – |
| PCLink UT/UP/US series | – | – | – | – | – | – | – | ✓ | – | – | – |
| HR2400 (10/20/30 ch) | – | – | – | – | – | – | – | – | – | – | ✓ |
✓ = correct driver for this device family | – = not applicable
Device-specific drivers: Each Yokogawa product family requires its own dedicated driver. DX devices use the DX driver, SMARTDAC+ GX/GP/GM devices use the GX driver, MX100 uses the MX driver, and so on. Using the wrong driver for a device will result in connection failure or incorrect data. The Yokogawa Suite bundles all 11 drivers in a single license so you can connect to any combination of Yokogawa hardware from one TOP Server instance.
How TOP Server connects to Yokogawa devices
The TOP Server Yokogawa Suite bundles all 11 drivers in a single license. Here is what each driver does, the specific hardware it covers, and the key configuration considerations for each.
DX Ethernet
Yokogawa DX Ethernet Driver
Connects to DX100/200 and MV100/200 series paperless recorders via Ethernet TCP/IP using the Yokogawa DX Data Acquisition Protocol. Supports up to 100 channels and 1,024 devices per channel, with each device running on a separate thread for optimized performance. Advanced features include configurable data handling to return out-of-range and error conditions as +INF/–INF, device clock synchronization with the system clock at startup, math computation initiation on the device at startup, configurable date/time format, and AS1 Advanced Security Option with device username/password.
Covers: DX102, DX104, DX106, DX112, DX204–DX230, DX1002–DX1012, DX2004–DX2048, MV100, MV200
GX Ethernet
Yokogawa GX Ethernet Driver
Connects to the SMARTDAC+ family — GX, GP, and GM series — over Ethernet TCP/IP using the Yokogawa GX/GP/GM Data Acquisition Protocol. Provides read access to process values, alarm states, and channel configuration from I/O, math, and communications channels. Note that write operations are not currently supported via this driver — the GX protocol interface is read-only for this integration path. Supports AS1 Advanced Security and device username/password authentication.
Covers: GX10, GX20 (data recorders), GP10, GP20 (data recorders with operator display), GM10 (modular data acquisition)
MX Ethernet
Yokogawa MX Ethernet Driver
Connects to the MX100 high-density modular data acquisition system over Ethernet TCP/IP using the Yokogawa MX Data Acquisition Protocol. The Stop MX on Shutdown feature optionally sends a measurement stop command to the MX100 when TOP Server shuts down — important for applications where uncontrolled measurement continuation during a system restart or maintenance window could create gaps or overlaps in the data record.
Covers: MX100 (all channel configurations and expansion units)
CX Ethernet
Yokogawa CX Ethernet Driver
Connects to the CX1000 and CX2000 controller-recorders over Ethernet TCP/IP using the Yokogawa CX Data Acquisition Protocol. Unlike the recorder-only families, the CX series supports both reads and writes via this driver, allowing OPC clients to read process values, setpoints, and alarm states, and to write setpoint changes and other control parameters back to the controller. The combination of control and recording data in a single instrument makes the CX series particularly valuable in batch process applications.
Covers: CX1000, CX2000
Green Ctrl Serial
Yokogawa Green Controller Serial Driver
Connects to Yokogawa's Green Series loop controllers using either direct RS-422 (4-wire) for UT37, UT38, and UP27 models, or PCLink protocol for the broader UT/UP/US controller families. Supports Ethernet Encapsulation via Ethernet-to-serial converter hardware, allowing modernization of serial PCLink networks by bridging them over TCP/IP without replacing the controllers. Supports broadcast messages using Device ID 0 for UT37 and PCLink devices.
Covers: UT37/38/UP27: RS-422 direct; PCLink: UT130/150/152/155, UT320/350/351/420/450/520/550/750, UP150/350/550/750, US1000
Ethernet Encapsulation for serial devices: All serial-based Yokogawa drivers in the suite support Ethernet Encapsulation. This allows a serial-to-Ethernet converter (Moxa NPort, Digi, and similar hardware) to bridge the serial protocol over TCP/IP. The TOP Server driver connects to the converter's TCP endpoint, and the converter handles the serial communication to the device. This is the recommended approach for modernizing serial-connected Yokogawa installations rather than running long serial cable runs to the TOP Server machine.
Frequently asked questions
Why does the GX/GP/GM driver not support writes when the CX driver does?+−
This reflects the fundamental difference in what these device families are designed to do. The SMARTDAC+ GX/GP/GM series are data acquisition and recording instruments — their primary function is measurement capture, not process control. The Yokogawa GX protocol is optimized for reading measurement data, alarm states, and channel configuration.
The CX series, by contrast, is a controller-recorder — it manages active control loops (temperature control, for example) in addition to recording. For a control instrument to be practically useful in a SCADA or OPC integration, write access to setpoints and control parameters is essential.
If you require write access to SMARTDAC+ devices, check whether the specific SMARTDAC+ model supports an alternative configuration path such as a web interface, SFTP file transfer, or a Modbus TCP register map.
What is the AS1 Advanced Security Option and which devices support it?+−
AS1 (Advanced Security 1) is an optional security feature on compatible Yokogawa devices that adds user authentication to the device's communication interface. When AS1 is enabled on the device, TOP Server must be configured with the device's username and password in the driver settings to establish a connection.
AS1 is supported by the DX Ethernet, GX Ethernet, DXP Ethernet, and CX Ethernet drivers in TOP Server. If you are having trouble connecting to a Yokogawa Ethernet device and the connection is being refused rather than timing out, AS1 being enabled on the device without a corresponding username/password configuration in TOP Server is the most common cause.
Can I connect to multiple different Yokogawa device families simultaneously in one TOP Server instance?+−
Yes, and this is one of the primary reasons the Yokogawa Suite bundles all 11 drivers in a single license. A single TOP Server installation can simultaneously maintain connections to a SMARTDAC+ GX20 via the GX Ethernet driver, a DX2040 via the DX Ethernet driver, an MX100 via the MX Ethernet driver, and a set of PCLink-connected UT controllers via the Green Controller Serial driver — all managed under one license and served to OPC clients as a unified tag namespace.
This is particularly valuable in plants where Yokogawa equipment has been acquired across multiple purchasing cycles and product generations.
What does "clock synchronization" mean in the Yokogawa driver context?+−
Several of the Yokogawa Ethernet drivers (DX, Darwin, and CX) include an option to synchronize the device's internal clock with the TOP Server machine's system clock at startup. When this option is enabled, the driver sends a time-set command to the connected Yokogawa devices when TOP Server starts, aligning the device clock to the server's time.
This feature matters for compliance and audit trail applications. Yokogawa recorders timestamp their logged data using their internal clock. If the device clock drifts over time and is not synchronized, timestamps on recorded data will diverge from the timestamps in the OPC historian. For regulated industries (pharmaceutical 21 CFR Part 11, food safety, ISO/IEC accredited labs), clock accuracy and traceability are often explicit compliance requirements.
How does the PCLink protocol work and how is it different from standard serial communication?+−
PCLink is Yokogawa's proprietary serial multi-drop communication protocol for the Green Series controller family. It operates over RS-422 (4-wire) and supports a master-slave network topology where the TOP Server PC acts as the master and the Yokogawa controllers are slaves. Multiple controllers can be connected to a single RS-422 bus (multi-drop), with each controller identified by a unique device address.
PCLink differs from generic serial protocols (Modbus RTU, for example) in that the frame structure, register model, and data organization are specific to the Yokogawa Green Series. A standard Modbus driver cannot talk to a PCLink device. The TOP Server Green Controller Serial driver implements the PCLink protocol specifically.
For the UT37, UT38, and UP27 models, direct RS-422 communication is used rather than PCLink framing — these older models predate the PCLink standard. The same Green Controller Serial driver handles both variants.
Does the Yokogawa Suite license cover all 11 drivers?+−
Yes. The TOP Server Yokogawa Suite is a single perpetual license that includes all 11 drivers: Yokogawa CX Ethernet, Darwin Ethernet, DX Ethernet, DXP Ethernet, GX Ethernet, MW Ethernet, MX Ethernet, Green Controller Serial, Darwin Serial, DX Serial, and HR2400 Serial. All drivers can be used simultaneously on the licensed machine — you can have multiple device families connected and served from a single TOP Server instance under one license, with no per-device or per-tag count restrictions.
Individual drivers are also available as standalone purchases if your environment only requires connectivity to a single Yokogawa device family. Contact Software Toolbox to identify the most cost-effective licensing option for your specific device mix.
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