Product details
Digital Process pH Sensor — RS485 Modbus, Integrated Transmitter
The InstroDirect IDH-100P Digital Process pH Sensor Pro – RS485 Modbus is the digital “Pro” variant with an integrated in-sensor transmitter and RS485 Modbus RTU output. Drops straight into Allen-Bradley, Siemens, Schneider, or Beckhoff PLCs without a separate pH transmitter. Automatic temperature compensation, calibration history, and sensor health diagnostics stream over the Modbus bus.
Technical Specifications
| Parameter | Specification |
|---|---|
| Measuring range | 0 – 12 pH |
| Temperature range | 0 – 60 °C |
| Pressure range | ≤ 0.2 MPa |
| Temperature compensation | NTC10K, NTC30K, NTC2.252K, PT100, PT1000 can be customised |
| Response time | ≤ 10 s |
| Factory slope | ≥ 95% |
| Zero potential | ± 10 mV |
| Reference type | Industrial reference |
| Reference material | Ag/AgCl |
| Reference electrolyte | Industrial Gel |
| Salt Bridge | Ceramic sand core |
| Membrane resistance | < 80 MΩ |
| Mounting Thread | Upper and lower 3/4″ NPT pipe threads |
| Shell material | PP |
| Length | 170 mm |
| Cable Connection | Integrated direct connection |
Typical Australian Applications
- SCADA-integrated WWTP process control
- Digital-native OEM analyser platforms
- IoT water-quality telemetry stations
- Food & beverage digital process monitoring
- Any Modbus-based plant PLC system
Why Engineers Choose the IDH-100P
- Eliminates the separate pH transmitter — the sensor IS the transmitter
- Open Modbus protocol — no Memosens or HACH SC lock-in
- Sensor-health diagnostics (slope, offset, impedance) log continuously to SCADA
- Plug-and-play for Australian integrators running AB, Siemens, Schneider, Beckhoff
- Typical 30–50% lower cost than equivalent Memosens CPS11D + Liquiline CM442 chain
Installation & Calibration
Wire RS485 directly into your PLC Modbus master. Default slave ID 0x01 at 9600 bps. Calibrate via Modbus function code 0x06 (write coil) to trigger two-point pH 4/7 or 7/10 calibration.
Frequently Asked Questions
Can this replace a HACH pHD or E+H CPS11D?
For basic continuous pH monitoring, yes — same measurement principle, same accuracy class. Key difference: open Modbus vs proprietary HACH SC / Memosens. Your PLC programmer no longer needs a vendor transmitter in the loop.
Does it stream sensor diagnostics?
Yes. Slope (mV/pH), offset at pH 7, glass-bulb impedance, reference impedance, temperature compensation status, and calibration history all stream over Modbus for predictive maintenance.
Australian Technical Support & On-Site Calibration
- Australian field engineers with 20+ years of industrial automation experience — phone and email support during AEST business hours.
- On-site pH calibration service across QLD, NSW, VIC — two-point buffer calibration (pH 4 / 7 / 10) with formal calibration certificate.
- Sensor health diagnostics — slope, offset, glass impedance, and reference junction checks.
- Replacement electrodes and buffer solutions available from InstroDirect’s broader water-analysis range.
Why InstroDirect vs Endress+Hauser or HACH in Australia
InstroDirect supplies the same grade of pH sensor that Australian councils, WWTP integrators, pharma plants, and food & beverage operators specify from Endress+Hauser (CPS11D, CPS31D, CPS41D, CPS71D) and HACH (pHD, Differential pH) — at a significantly lower landed cost and without vendor lock-in.
| Factor | InstroDirect | Endress+Hauser / HACH |
|---|---|---|
| Digital protocol | Open RS485 Modbus RTU — integrates with Allen-Bradley, Siemens, Schneider, Beckhoff, or any SCADA | Proprietary Memosens / HACH SC — locked to the vendor’s transmitter |
| Technical support | Australian field engineers with 20+ years automation experience | Offshore ticket queue or authorised distributor |
| On-site calibration | InstroDirect service across QLD, NSW, VIC with formal certificate | Third-party authorised service network, longer turnaround |
| Price | Parallel-import, no distributor margin stack — typically 30–50% below equivalent E+H / HACH pricing | Premium brand with distributor markup |
| Replacement parts | Standard glass-bulb and reference cartridges | Proprietary Memosens head, tied to the brand |
Moving away from Memosens or SC digital protocols frees you to mix and match sensors with any Modbus-capable transmitter or PLC. InstroDirect pH electrodes drop straight into an existing control system without a new proprietary transmitter.
Request a Trade Quote
Panel builders, integrators, council water departments, and pharma/process teams get volume trade pricing. Submit a quote request and we’ll respond within one business day.
