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RF & Wireless Systems · Hardware

Wireless RS485 Modem

Model code: EL485L-S

Extend your RS485 line wirelessly — no trenching, no cable.

Request a quote Specifications
EL485L-S wireless RS485 modem: light grey ABS wall box with front label and LEDs, antenna on top

Overview

The problem. Most PLCs, RTUs, energy analyzers and meters speak RS485/Modbus RTU. When devices are spread across a site (wells, reservoirs, pump stations, transformers, silos), running an RS485 line means trenching, conduit and cable costs; road and stream crossings or third-party land can make the line impossible. Existing cable runs break due to lightning, moisture and digging accidents, and finding the fault takes hours. GSM modems bring subscriptions and dependence on network coverage.

The solution. The wireless RS485 modem is installed at both ends of the RS485 line and carries the serial data transparently over radio. The PLC/SCADA software does not change; the modem looks like a cable. The current EL485L-S links up to 10 km in open field (1200 bps, per the technical datasheet) with 500 mW output power; 40 channels let several links run side by side on the same site. With master/slave firmware, one central station can poll several remote ends (Modbus polling).

New series. The same function is to be delivered with an EM-G0L-433 or EM-G0L-868 module and the EC-485 carrier board (I/O Carrier Boards): LoRa modulation gives higher sensitivity and interference immunity at low data rates, the RS485 port becomes isolated, and an optional Wi-Fi/Ethernet Modbus TCP bridge (Wireless Gateway / RTU) is offered in the same housing.

Two EL485L-S modems carrying the RS485 line between a PLC and a drive in two remote panels
In use
Old and new series: EL485L-S wall box next to DIN-rail EM485-433 and EM485-433-GW
Product family

Features

  • Transparent serial bridge: no drivers or configuration on the PLC/SCADA side; it behaves like an RS485 cable.
  • Master/slave firmware: central polling, RF timeout flag; point-to-point or star topology.
  • Adjustable power (10–500 mW) and 40 channels: neighboring links on separate channels; lower power at short distances to reduce interference.
  • Large packets (500 bytes): long Modbus responses (multi-register reads) in a single RF packet.
  • Optional modules: directional antenna kit, DIN-rail power supply, RS232 converter.
  • TargetIsolated RS485: 2.5 kV isolation and a termination switch.
  • Target"Link OK" relay output and RSSI/SNR indication: link quality via LEDs and the service port.
  • TargetModbus RTU address routing: one master, N remote ends; frames are forwarded to the right end by Modbus address.
  • TargetRepeater profile: range extension through an intermediate station.
  • TargetModbus TCP bridge: with the dual-radio LoRa/Wi-Fi module (EM-G0LW-433).
  • TargetOTA updates: remote firmware updates.

Generations and variants

Generations and variants
Model codeHardwareBandInterfaceStatusRequest a quote
EL485L-SSi4463868–869 MHz (433–434 MHz option listed in the datasheet)RS485, D-SUB-9 + KLS4 terminal blockIn the field (Mersin, Şanlıurfa)Request a quote: EL485L-S
EL485L-S-M / -SSi4463869 MHzMaster / slave firmwareIn the fieldRequest a quote: EL485L-S-M / -S
EM485-868TargetNew series: EM-G0L-868 + EC-485868 MHz (SX1262)Isolated RS485 + optional RS232PlannedRequest a quote: EM485-868
EM485-433TargetNew series: EM-G0L-433 + EC-485433 MHz (SX1268)Isolated RS485PlannedRequest a quote: EM485-433
EM485-433-GWTargetNew series: EM-G0LW-433 + EC-485433 MHz + Wi-FiRS485 + Modbus TCP bridgePlanned (shared with the gateway)Request a quote: EM485-433-GW

Specifications

Values marked “Target” are design targets, next-generation values or chip-vendor data; they are updated as measurement and certification are completed.

Radio
Frequency band (EL485L-S)868–869 MHz ISM (the datasheet also lists a 433–434 MHz option)
Frequency band (new series)868 MHz (SX1262) or 433 MHz (SX1268) versionTarget
Channels (EL485L-S)40, selectable
Channels (new series)8 (433 MHz plan)Target
Output power (EL485L-S)500 mW (27 dBm); adjustable 10–500 mW
Output power (new series)+22 dBm; ETSI 14 dBm ERP limit at 868 MHzTarget
Receiver sensitivity (EL485L-S)−126 dBm
Receiver sensitivity (new series)−129 dBm @ SF11 (chip datasheet)Target
Modulation (EL485L-S)(G)FSK (Si4463)
Modulation (new series)LoRa SF7–SF12Target
RF data rate (EL485L-S)0.6–300 kbps
RF data rate (new series)0.3–62.5 kbps (LoRa)Target
Antenna connector (new series)SMA female, 50 ΩTarget
Range
Open field (EL485L-S)Up to 10,000 m @ 1200 bps (datasheet claim; line of sight)
Open field (new series)≥ 5 km @ SF10, 2 dBi antenna, 3 m heightTarget
Industrial / indoors (new series)≥ 300 mTarget
Communication & security
Coding (EL485L-S)CRC-16 (ITU), address / channel; no encryption
Encryption (new series)AES-128-CCM; NetID + 16-bit addressTarget
Links on the same site (EL485L-S)40 channels; each link on its own channel
Systems on the same site (new series)≥ 8 independent networks via channel × NetIDTarget
Performance & fail-safe
Latency (EL485L-S)Depends on baud rate and packetization
Latency (new series)< 100 ms @ SF7, short packetTarget
On communication loss (EL485L-S)Through the PLC's Modbus timeout; the PLC/RTU logic defines the safe state
"Link OK" output (new series)Relay output, 1–60 s adjustableTarget
Watchdog (EL485L-S)Microcontroller WDT (PIC)
Watchdog (new series)Independent hardware watchdog (IWDG)Target
Power
Supply (EL485L-S)12–24 VDC
Supply (new series)9–36 VDC; reverse-polarity + TVS protectionTarget
Consumption (new series)~118 mA @ 3.3 V while transmitting (module) + carrier boardTarget
Interfaces
Serial interface (EL485L-S)RS485 (D-SUB-9 + KLS4 terminal block); 1.2–115.2 kbps selectable; packet ≤ 500 bytes
Serial interface (new series)Isolated RS485, 115.2 kbps + optional RS232; 2× DI, 2× DO (EC-485)Target
Protocol (EL485L-S)Transparent serial; works with Modbus RTU
Protocol (new series)Transparent + Modbus RTU address routing (address → remote end) + Modbus TCP (GW version)Target
Mechanical & environmental
Housing (EL485L-S)83 × 137 × 34 mm, IP55
Housing (new series)DIN-rail housing, 2 modules (36 mm); IP20 (inside a panel)Target
Mounting (EL485L-S)Wall / panel (box)
Mounting (new series)35 mm DIN railTarget
Operating temperature (EL485L-S)−40…+85 °C
Operating temperature (new series)−25…+70 °C (terminal / relay limit)Target
Humidity (new series)5–95 %, non-condensingTarget
Warranty & service
Warranty / spare parts2-year manufacturer warranty; 15-year parts availability; made in Ankara

Applications

  • Water and sewage utilities
  • Well–reservoir–pump stations
  • Transformer substations
  • Solar / wind farms
  • Silo, weighing and kiln lines
  • Distributed meters in industrial zones
  • Irrigation pumps and valves
  • OEM RS485 devices
  • Water and sewage utilities: RTU links between wells, reservoirs and pump stations; for the SCADA side see SCADA & Industrial Automation.
  • Energy: analyzer reading at transformer substations and solar/wind farms.
  • Industry: extending silo, weighing, kiln and drive lines; distributed meters within industrial zones.
  • Agriculture: connecting irrigation pump and valve controllers to the control center (Wireless Irrigation Control System).
  • OEM: the Elmes Module Series for manufacturers who want to make their own RS485 devices wireless.

The EL485L-S was deployed in 2018 in Mersin and Şanlıurfa for SCADA/RTU links. Antenna height is decisive for range; long links use directional antennas (Industrial RF Antenna Series).

Compliance & documentation

For the current EL485L-S, the manufacturer's technical datasheet contains a regulatory declaration; there is no accredited test report. Documentation for the new series is being prepared step by step according to the plan below, starting at module level.

  • Turkish Radio and Telecommunications Terminal Equipment (Class 2) Regulation — EL485L-S
    Manufacturer's declaration in the technical datasheet
    Self-declared
  • CE – RED 2014/53/EU (EN 300 220-2, EN 301 489-1/-3, EN 62368-1) — new series
    Step by step, starting at module level
    Target
  • BTK (Turkish ICT Authority) application — new series
    Separate applications for 433 MHz and 868 MHz
    Target
  • RoHS declaration
    Target
  • CE declaration of conformity and user manual
    Target

Frequently asked questions

Do I need to change the software in my PLC?

No. The modem is a transparent serial bridge; we only recommend increasing the Modbus timeout to allow for the RF delay.

How many links can run on the same site without interfering?

The current EL485L-S has 40 channels and each link is put on its own channel. The new generation targets at least 8 independent networks through channel and network ID (NetID).

Is the range really 10 km?

The 10 km figure in the datasheet applies to open field, line of sight and 1200 bps. Indoors and over obstructed terrain it is much shorter. Range is increased with antenna height and directional antennas (Yagi / J-pole).

Can I connect one master to several RTUs?

Yes; the master/slave firmware runs in a star topology. The RTUs must have different Modbus addresses.

What happens if the RF link is lost?

No data reaches the serial port and the PLC raises a Modbus timeout; the PLC/RTU logic defines the safe state. The new generation adds a "link OK" output that can be wired to a panel alarm.

Is a frequency license or subscription required?

No. The modem works in the 433/868 MHz ISM band within legal limits according to its datasheet and needs no frequency license. There is no subscription.

Do the current EL485L-S and the new-generation modem work together?

No; they use different modulation (FSK vs. LoRa). Both generations can run side by side on the same site as separate links.

What about warranty and service?

2-year manufacturer warranty and 15-year parts availability. Service is in Ankara; the new generation targets remote OTA updates.

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