Ursalink Controller Replacement: Which Milesight Controller Replaces a UC1152?
TL;DR: Ursalink merged with Milesight in December 2020 and its products now carry the Milesight name, so an Ursalink controller is replaced with a current Milesight model. For a UC1152 that used its relay, its 3 to 24 V digital input or RS232, the like-for-like swap is the UC300. For a Modbus-only job, the UC100 is enough. The battery UC50x controllers are Milesight’s replacement for the UC11-N1, but their inputs are 3.3 V logic, so they must not be wired in place of a UC1152’s 24 V input or relay.
Last updated: 14 September 2026
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Key takeaways
- Ursalink is now Milesight. When the companies merged in December 2020, Yeastar announced that Milesight and Ursalink would operate under the Milesight brand.
- The Ursalink UC1152 had one opto-isolated digital input, one 3 A relay, an RS232 port and an RS485 port with Modbus master, running from 5 to 24 V DC.
- The closest Ursalink controller replacement is the Milesight UC300: same 5 to 24 V supply, the same 3 to 24 V input range and the same 3 A relay rating, with more of each.
- For Modbus RTU only, the UC100 reads up to 32 registers from up to 32 devices for £38.90 ex VAT.
- The battery UC50x controllers use 3.3 V logic GPIO, not opto-isolated 24 V inputs or relays, so they are not a drop-in swap for a UC1152 in a panel.
What happened to Ursalink?
Ursalink merged with Milesight and Yeastar in December 2020, and its IoT products continued under the Milesight name. Yeastar’s merger announcement states that Milesight and Ursalink would operate under the Milesight brand, while Yeastar continued under its own.
That is why engineers searching for an Ursalink controller today find Milesight part numbers. The LoRaWAN controllers, gateways and routers that carried the Ursalink logo belong to the same product lines Milesight sells now, and the older models have been replaced by newer ones with different part numbers.
The practical question is rarely about the brand. It is about a specific unit in a specific panel: an Ursalink controller that has failed, or a site being expanded, where the installer needs a current part that fits the same wiring.
What did the Ursalink UC1152 do?
The UC1152 was an Ursalink controller for panels: mains powered, LoRaWAN, with remote I/O. According to the Ursalink UC1152 user guide, it ran from 5 to 24 V DC and had a single terminal strip carrying power, an RS232 port, an RS485 port, one digital input and one relay output.
| UC1152 terminal | What the Ursalink user guide says |
|---|---|
| Power | 5 to 24 V DC, 12 V nominal |
| RS232 | RXD, TXD and GND |
| RS485 | A and B, used for Modbus master |
| Digital input | Opto-isolated, triggers from 3 to 24 V DC |
| Relay output | 3 A SPDT, up to 250 V AC or 30 V DC |
| Configuration | Micro USB to a PC |
Two details in that guide matter for a replacement. Milesight’s own controller FAQ confirms that the UC1152’s Modbus master works on the RS485 port only. And the user guide warns against installing the unit inside a metal enclosure unless the antenna is mounted outside, which is still good advice for any Ursalink controller replacement.
Which Milesight controller replaces a UC1152?
For most panels, the Milesight UC300 replaces a UC1152 Ursalink controller like for like. It runs from the same 5 to 24 V DC, its digital inputs accept the same 3 to 24 V DC range, and its relays carry the same 3 A at 30 V DC or 250 V AC. Everything the old Ursalink controller was wired to has a matching terminal on the UC300.
It also adds a great deal. The UC300 has four digital inputs instead of one, two relays instead of one, two 4-20 mA inputs, two 0-10 V inputs and two PT100 inputs, and it reads up to 32 Modbus registers from up to 32 devices on RS485. It mounts on DIN rail and has an SMA antenna connector, so the antenna can go outside a metal panel.
| Ursalink UC1152 | Milesight UC300 | |
|---|---|---|
| Supply | 5 to 24 V DC | 5 to 24 V DC or USB-C |
| Digital inputs | 1, opto-isolated 3 to 24 V | 4, opto-isolated 3 to 24 V |
| Relay outputs | 1, 3 A SPDT | 2, 3 A SPDT |
| Analogue inputs | None | 2 × 4-20 mA, 2 × 0-10 V, 2 × PT100 |
| Serial | RS232, RS485 Modbus master | RS232, RS485 Modbus RTU |
| Configuration | Micro USB to a PC | NFC, USB-C or downlink |
| Price ex VAT | Discontinued | £104.74 |
When is a UC100 enough?
If the Ursalink controller was only ever reading a meter or a controller over Modbus RTU, and its relay and input were unused, the Milesight UC100 does that job for far less. It has one RS485 port, reads up to 32 Modbus registers from up to 32 devices, and runs from 5 to 24 V DC at under 0.5 W.
At £38.90 ex VAT, the UC100 is the cheapest way to put a Modbus heat meter, energy meter or plant controller onto LoRaWAN. It has no digital inputs, no relays and no RS232, so check the old wiring before choosing it. Our comparison of the UC100, UC300, UC501 and UC502 sets the four side by side.
What about the UC11-N1 and the UC50x?
Milesight’s controller FAQ states that the UC11-N1 was nearing end of life and replaced by the UC50x series. The UC501 and UC502 are the battery or solar powered, IP68 members of that family, built for outdoor data logging rather than for a mains-powered panel.
That makes them excellent replacements for a battery powered Ursalink controller logging a 4-20 mA transmitter or an SDI-12 probe in the field. They have two analogue inputs switchable between 4-20 mA and 0-10 V, an SDI-12 port, an RS232 or RS485 port and switchable power outputs to feed the sensors they read. The UC501 charges from its built-in solar panel; the UC502 runs on replaceable lithium batteries from -30°C to 70°C.
What is the wiring trap?
The trap is treating a UC50x as a drop-in replacement for a UC1152 or any other panel-mounted Ursalink controller. The UC50x digital ports are GPIO pins with 3.3 V logic: low from 0 to 0.8 V, high from 2.5 to 3.3 V, and a maximum of 20 mA. The UC1152’s input took 3 to 24 V through an opto-isolator, and its output was a relay rated at 3 A.
Wire a 24 V status signal from a panel into a UC50x GPIO and you risk damaging it. Expect a UC50x output to switch a contactor coil the way a relay did and it will not. Neither mistake shows up on a parts list, because all three products are sold as LoRaWAN controllers.
The rule is simple. If the old Ursalink controller used its relay, its digital input on a 12 or 24 V circuit, or its RS232 port, replace it with a UC300. Use a UC50x only where the job is battery or solar logging of sensors that the UC50x can power and read directly.
What changes on the network side?
A replacement for an Ursalink controller joins the network as a new device and sends a different uplink format, so plan for three changes. Register the new device on your LoRaWAN network server with its own keys, load the decoder for the new model into your platform, and remap any dashboards or alarms that pointed at the old device’s fields.
Configuration also changes for the better. The old Ursalink controller range was configured over micro USB from a PC, while current Milesight controllers are set up from a phone over NFC, from PC software over USB-C, or remotely by downlink. If the site’s gateway is also old Ursalink hardware, it is worth checking its firmware and network server support at the same visit. Our guide to getting legacy plant into SCADA over Modbus and MQTT covers the register mapping side.
Frequently asked questions
Is Ursalink the same company as Milesight?
Yes. Ursalink, Milesight and Yeastar merged in December 2020, and Ursalink’s products continued under the Milesight brand, according to Yeastar’s announcement of the merger.
What replaces the Ursalink UC1152?
The Milesight UC300 is the closest match: the same 5 to 24 V DC supply, opto-isolated 3 to 24 V digital inputs and 3 A relays, with more inputs and outputs and analogue channels added.
Can a UC501 or UC502 replace a UC1152?
Not in a panel wired for a 24 V input or a relay. The UC50x digital ports are 3.3 V logic GPIO with a 20 mA maximum. They suit battery or solar data logging rather than panel I/O.
Is there a cheaper replacement for a Modbus-only Ursalink controller?
Yes. The UC100 reads up to 32 Modbus registers from up to 32 devices on RS485 and costs £38.90 ex VAT, but it has no digital inputs, relays or RS232.
Do I need a new decoder after replacing an Ursalink controller?
Yes. The replacement is a different model with a different uplink format, so load its decoder into your platform and remap dashboards and alarms to the new fields.
Replace by function, not by name
An Ursalink controller is replaced by whichever current Milesight model matches what the old unit was wired to do. For panel I/O that is almost always the UC300, for Modbus alone the UC100, and for battery logging in the field the UC501 or UC502.
See the UC300 on Indiott for live pricing, or send us a photo of the old terminal strip and an engineer will confirm the right replacement within one working day.
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