Bullhorn RM4210 and RM4250 Coupon Test Station Remote Monitors

Bullhorn RM4210 and RM4250 RMUs remotely monitor AC coupon test stations, like the Triton triple-coupon test station, to help optimize AC corrosion mitigation systems.

Why Choose Bullhorn RM4210 and RM4250 Remote Monitors?

We engineered Bullhorn RM4210 and RM4250 Remote Monitoring Units to provide continual AC corrosion threat tracking.

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A long-lasting battery and satellite (RM4210) or cellular (RM4250) connectivity means these remote monitors provide reliable, near-instantaneous communication. The RM4210 and RM4250 offer:

Quick Installation – Install only takes a few minutes. Wire the RMU to the test station, plug in the batteries, and affix the RMU to the top of the test station or pole. Installation is even faster on a TRITON Test Station since they come ready to plug into a Bullhorn RMU.

Easy Configuration & Economical Data Plans – These RMUs have Bluetooth built-in, making it easy to configure them in the field using Bullhorn® Tools. You do not need extra adapters to connect to the device. Alternatively, you can also configure the RMU via Bullhorn Web from the comfort of your office.

Highly Accurate – Measure within one percent of reading accuracy throughout the range, with auto-calibration and auto-zero for every measurement. For example, a one mV measurement will be accurate within ±10 microvolts. Accuracy is especially critical when using a small AC coupon.

Reporting – Quickly identify problem areas and ensure mitigation effectiveness using flexible reports and graphs.

Value – We can bundle RM4210 or RM4250 with the award-winning Triton triple-coupon test station, so that you can order your AC monitoring equipment in one purchase.




AC current density, DC current density,
AC pipe-to-soil, DC pipe-to-soil, PCR
AC current drain or voltage, instant off

DC voltage range:

±100 V

AC voltage range:

0-100 V

AC Current Range:

0-200 mA

Input impedance:

10 MΩ


> 200 V

Instant Of

IR drop edge delay:

IR drop edge delay: 200 ms


Bullhorn Tools Mobile via Bluetooth low energy


RM4210 – IsatData Pro Satellite (Inmarsat)

RM4250 – LTE Cat-M Cellular (AT&T)

Software Interface

Bullhorn Web

Bullhorn Tools for iOS and Android

Software Interface

Internal, field-replaceable primary and secondary batteries

3-7 year life when recording measurements hourly or daily with weekly transmissions

Additional solar or DC input voltage: 10-24 V DC


Ø 6.06” x 3.96” H (8.22” H with test station adapter)

Data Integrity

Data stored in nonvolatile (EEPROM) memory

Queued two-way communication (communication to the RMU is queued in Bullhorn Web and is sent the next time the unit wakes up to transmit)



-30° C to +60° C

Safety and Compliance

Certification mark:


Tested Safety Standards:
CAN/CSA C22.2 No. 61010-1-2012
CAN/CSA C22.2 No. 61010-2-030:2012

Thank you for your interest in the RM4210 and RM4250. Fill out the form below and we'll be in touch as soon as possible.