UC100 vs UC300 vs UC501 vs UC502: Which LoRaWAN Modbus Controller Do You Need?

Short answer: All four Milesight units are LoRaWAN Modbus controllers, but only one is Modbus-only. Choose the UC100 if you just need Modbus RTU over RS485 indoors — one port, no other inputs, and the cheapest of the four. Choose the UC300 for mixed panel wiring: 4 digital inputs, 2 relay outputs, 4-20 mA and 0-10 V analogue, PT100 RTD, RS232 and RS485. Choose the UC501 or UC502 outdoors where there is no mains — both are IP68 with identical I/O, but the UC501 is solar-charged and the UC502 runs on three replaceable lithium cells down to -30°C.

Which LoRaWAN Modbus controller do I need?

Choose the UC100 if the equipment you want to monitor is already a Modbus RTU device — an energy meter, a VSD, a heat meter — and you only need its registers on LoRaWAN. It has one RS485 port and nothing else: no digital inputs, no analogue inputs, no relay. It reads up to 32 Modbus registers across as many as 32 devices, draws under 0.5 W from 5-24 VDC or USB-C, and at 70 × 45 × 13 mm it fits inside the meter cabinet you are already opening.

Choose the UC300 if the signals in the panel are mixed and not all of them are Modbus. It is the only one of the four with relay outputs (2 × SPDT, 3 A at 30 VDC or 250 VAC) and dedicated PT100 RTD inputs, alongside 4 opto-isolated digital inputs, 2 × 4-20 mA and 2 × 0-10 V analogue inputs, and both RS232 and RS485. It is also the only model here that DIN-rail mounts. Its IP30 metal case belongs inside an enclosure, not on an outside wall.

Choose the UC501 if the assets are outdoors with no mains supply but reasonable daylight — a tank on a farm, a roadside cabinet, a rooftop plant skid. The IP68 housing withstands 1 m underwater for seven days, and an embedded 6 V / 1.7 W solar panel keeps two 2550 mAh rechargeable ICR18650 cells topped up. It is the only battery-powered model of the four that also supports Class C.

Choose the UC502 if the site is outdoors and dark, cold, or rarely visited — a buried chamber, a culvert, a shaded valley. It swaps solar for three replaceable 9000 mAh ER26500 Li-SOCl2 cells and widens the operating range to -30°C to 70°C, the coldest-rated of the four. It is also the most expensive of the four.

UC501 vs UC502: what is actually different?

Almost nothing on the input side. Both give you 2 × GPIO, 2 × analogue inputs switchable between 4-20 mA and 0-10 V, one serial port switchable between RS232 and RS485 with Modbus RTU, one SDI-12 v1.4 port, the same M12 A-coded connectors, the same 116 × 116 × 45.5 mm IP68 enclosure and the same switched 3.3 V and 5/9/12 V sensor supply rails. Three things differ:

• Power — UC501: embedded solar plus 2 × 2550 mAh rechargeable ICR18650. UC502: 3 × 9000 mAh replaceable ER26500 Li-SOCl2.
• LoRaWAN class — the UC501 supports Class A and Class C; the UC502 is Class A only, so it cannot hold a receive window open for on-demand downlink control.
• Temperature — UC501: -20°C to 60°C. UC502: -30°C to 70°C.

The UC502 is not a newer or upgraded UC501, and the UC501 is not the solar accessory version of it. They are two answers to one question: can this location see the sky? If yes, UC501. If no, UC502.

Do any of these replace a LoRaWAN gateway?

No. A UC-series controller is an end device, not a gateway — it converts wired signals into LoRaWAN uplinks, but something still has to receive them. All four here are the -868M variant, which covers the EU868 band that UK LoRaWAN networks use, and each still needs a gateway in range plus a network server to decode the payload. If you already have gateway coverage on site, the controller is all you are adding.

Frequently asked questions

Which of these controllers can be installed outdoors?

The UC501 and UC502 are rated IP68 and withstand 1 m underwater for 7 days, so they mount directly on a wall or pole outdoors. The UC100 and UC300 are IP30 only and must go inside a cabinet or enclosure.

How many Modbus devices can the UC100 and UC300 read?

Both read up to 32 Modbus registers and connect up to 32 Modbus RTU devices over RS485, at 1200 to 115200 bps. The UC501 and UC502 datasheets confirm Modbus RTU support on their RS485 port but do not quote a register or device capacity, so we would not assume it matches.

Do the UC501 and UC502 both support LoRaWAN Class C?

No. The UC501 supports OTAA/ABP in Class A and Class C. The UC502 is Class A only. If you need on-demand downlink control of a GPIO output rather than control on the next scheduled uplink, that difference matters.

Can these controllers power the sensors wired to them?

The UC501 and UC502 provide 2 × 3.3 V continuous outputs plus 2 × switchable 5/9/12 V outputs that energise for 0 to 10 minutes before data collection. The UC100 and UC300 datasheets do not list sensor power output rails.

Which one can switch equipment on and off, not just monitor it?

The UC300 is the only model of the four with relay outputs — 2 × SPDT rated 3 A at 30 VDC or 250 VAC. The UC501 and UC502 have 2 × GPIO that can be software-configured as digital outputs at logic level (max 20 mA), which is a signal, not a switched load. The UC100 has no outputs at all.

Which model mounts on DIN rail?

Only the UC300 lists DIN rail mounting alongside desktop and wall mounting. The UC100 is desktop or wall-screw mounted, and the UC501 and UC502 are wall or pole mounted.