MDT
Modbus Data Transceiver
Standard, MAX and LoRaWAN® Systems
Product Overview
The Modbus MDT connects one Modbus electric or BTU meter directly to the Tehama cloud. It auto-detects the meter type and reads six predefined registers required for sub-metering: Consumed Energy, System Power, Power Factor, and Phase A/B/C Power. Other registers are available on special order.
Initial firmware supports AccuRev 1310, Dent PS3, Leviton 4100 and EZmeter. The MDT is offered in all Tehama radio families—Standard, MAX and the new LoRaWAN®. A 3.3 V line-power option is available; otherwise two field-replaceable AA lithium batteries power the unit for up to eight years.
Specifications
| Specification | Details |
|---|---|
| Input | 3-wire Modbus RTU (19 200 bps, Port 1 recommended) |
| MDT Data Storage | • -Mod: no local storage • -ModT: > 2 300 time-stamped points (≈ 24 days @ 15 min) |
| Data Resolution | • -Mod: 1 h (Standard/MAX) · 4 h (LoRaWAN) • -ModT: 15 min, top-of-hour synchronised * |
| Radio | 902 – 928 MHz · FCC/IC certified Open-field ≈ 1 mi (Standard) Open-field ≈ 10 mi (MAX & LoRaWAN) ** |
| LED | Green / Amber / Red – power & RF-link status |
| Operating Environment | -20 ° to 145 °F · ≤ 90 % RH, non-condensing |
| Power | Two AA lithium batteries (optional 3.3 V DC line power) |
| Typical Battery Life | 6 – 8 yrs @ 50 – 90 °F (reduced at extremes) |
| Dimensions | 4.3″ × 2.2″ × 1.2″ |
| Warranty | Five years (batteries excluded). See our warranty page. |
Continual product enhancements may cause specifications to change without notice.
* Time-of-Use on LoRaWAN requires a data subscription.
** Actual range varies with installation & topography.
Models
| Standard System | Model # | Description |
|---|---|---|
| Modbus MDT | TW-160B-Mod | Single meter input · 1-h data · no memory |
| Modbus MDT, Time-of-Use | TW-160B-ModT | 15-min ToU data with on-board memory (guaranteed *) |
| MAX System | Model # | Description |
| Modbus MDT | TW-170B-Mod | Single meter input · 1-h data · no memory |
| Modbus MDT, Time-of-Use | TW-170B-ModT | 15-min ToU data with on-board memory (guaranteed *) |
| LoRaWAN® System | Model # | Description |
| Modbus MDT | TW-180B-Mod | Single meter input · 4-h data · no memory |
| Modbus MDT, Time-of-Use | TW-180B-ModT | 15-min ToU data with on-board memory (guaranteed */**) |
* Adequate Repeater / Gateway coverage required. ** LoRaWAN ToU requires a data subscription.
Note: Standard, MAX and LoRaWAN products are NOT cross-compatible.
See AN-119 for additional information.
MDT Configuration
All MDTs ship pre-configured; register units and count factors are read automatically from the meter. Devices ship powered-off—press the hidden button beneath the logo (or swipe a magnet on submersible models) to power on. The LED provides the same green/amber/red feedback as other MDTs.
Implementation Details
• One MDT per meter (point-to-point Modbus).
• Set meter baud to 19 200 bps on Port 1 for fastest pairing.
• The MDT RadioID ends in “0”; additional Modbus registers appear as virtual MDTs ending “1”.
Wiring Guide
Device Placement
Warning: All radio devices should be placed at least 8 in (20 cm) away from people to minimise RF exposure.
- Ideal: mount upright on wallboard, clear of metal conduit or copper piping.
- Use the integrated key-hole slot to hang the MDT on a #6 drywall screw, then tighten.
- Avoid mounting directly on metal surfaces or in metal enclosures; both degrade RF performance.
- The antenna null is along the long axis of the case—orient vertically for best signal.
