YOKOGAWA YS1700-100/A06/A31 | Isolated 2-Wire Transmitter Input

• Model: YS1700-100/A06/A31
• Brand: Yokogawa
• Series: YS1000
• Core Function: Programmable single-loop process control
• Type: Programmable Indicating Controller
• Key Specs: 100 VAC / 24 VDC power; isolated 2-wire transmitter input; RS-485 communication

Product Introduction

Yokogawa YS1700-100/A06/A31 is a programmable indicating controller configured for single-loop process applications. The -100 specification identifies the basic type with 100 VAC / 24 VDC common power, while /A06 provides an isolated two-wire transmitter input and /A31 adds RS-485 communication.

For field instruments tied into older Yokogawa control architectures, this configuration is particularly useful because RS-485 supports PC-Link, Modbus, YS protocol, and peer-to-peer communication. Yokogawa also specifies direct RS-485 communication with CENTUM CS3000/VP for appropriate configurations.

Key Technical Specifications

The nonvolatile memory design avoids dependence on a battery or capacitor for memory backup, which reduces one routine maintenance concern. Yokogawa also describes the platform as having dual CPUs for control and display functions.

Application and Selection Notes

This controller fits process skids, chemical plants, utilities, temperature loops, pressure control, flow systems, and legacy DCS-related installations where one programmable control loop is required.

The /A06 option deserves particular attention. It is an isolated two-wire transmitter input, not a generic analog input. If the existing transmitter loop depends on that isolation, selecting an apparently similar controller without /A06 can change the electrical behavior of the installation.

The /A31 communication option is equally important. RS-485 supports several Yokogawa communication modes, including Modbus, so the replacement should retain the same communication configuration as the original unit.

Replacement and Compatibility Notes

Power configuration: Verify the original supply code before ordering. The -100 configuration is associated with 100 VAC / 24 VDC common power. A 220 VAC version uses a different specification code.

Input configuration: Keep /A06 when the field device requires an isolated two-wire transmitter input.

Communication option: /A31 is a factory-specified option. Yokogawa states that Ethernet /A34 cannot simply be added in the field; RS-485 or DCS-LCS retrofits require return to Yokogawa.

Program conversion: When replacing older YS-series controllers, do not assume the old program can simply be copied across. Yokogawa provides YSS1000-based conversion and replacement procedures.

Personally, I would photograph the complete model code and communication settings before removing the old controller. That small check can save a full commissioning cycle.

Quality Inspection and Testing

For a stocked controller, the inspection sequence should include:

1. Inbound inspection: Verify nameplate, model code, serial number, terminals, display, keys, enclosure, and signs of previous repair.
2. Live test: Power the controller using the correct supply and check startup, display operation, keypad response, input measurement, and RS-485 communication.
3. Electrical testing: Check supply circuitry, grounding continuity, and insulation condition as applicable.
4. Configuration verification: Record firmware and configuration information, input range, communication settings, and programmed parameters.
5. Final QC: Photograph the unit, record test results, protect terminals and display, and package with suitable cushioning.

Test photos or video can be supplied when available.

Warranty and Availability

Condition: Confirm whether the offered unit is New Original (New Surplus), used, or refurbished.

Stock: Actual warehouse availability should be confirmed before purchase.

Lead Time: Subject to physical stock, inspection, packaging, and export processing.

Warranty: Supplier warranty applies according to the agreed commercial terms.

The YOKOGAWA YS1700-100/A06/A31 is a configuration-specific programmable controller. For international procurement, verify the power code, /A06 input option, /A31 communication option, software configuration, condition, country of origin, and export documentation before shipment.