Cellular modem (complete industrial modem or DTU that connects serial or USB equipment to a 4G/LTE network)

01

Match the bands, LTE category and fallback to the region

USR lists its LTE Cat 1 devices (USR-DR502-E, USR-G771-E and the WH-LTE-7S1-E module) on LTE FDD bands B1/B3/B7/B8/B20/B28 with GSM/GPRS/EDGE at 900/1800 MHz, LTE speeds of 10 Mbps down and 5 Mbps up (Rel.13) and GPRS at 85.6 kbps. It gives transmit power of 23 dBm ±2 dB on LTE, 33 dBm on GSM 900 and 30 dBm on GSM 1800, and receive sensitivity of -97.5 to -98.5 dBm across its LTE bands and -109.5 dBm on GSM 900. In one application note it says the module switches to GPRS "in the case of unstable LTE". [1]

Teltonika describes its TRM240 as an industrial-grade USB LTE Cat 1 modem with 3G and 2G, a rugged housing and an external antenna, aimed at "upgrading existing industrial equipment". [3]

Editorial conversion: 23 dBm is 10^(23/10) ≈ 200 mW and 33 dBm ≈ 2 W; the 11 dB gap between USR's GSM 900 sensitivity (-109.5 dBm) and its LTE B8 sensitivity (-98.5 dBm) is a factor of about 12.6 in received power. [1] Check which bands and fallback networks your operator will keep running before choosing.

Give the modem maker the countries and operators, required bands and LTE category, fallback (2G or 3G) needs, host interface and serial settings, protocol (transparent, TCP/UDP, MQTT, HTTP, PPP), server and security needs, SMS use, power supply, housing and mounting (DIN rail, panel, board), antenna type and cable, temperature range, certifications (CE, operator approvals) and quantity.

02

Choose the host port, data mode and power

USR's table gives one RS485 terminal (DR502-E, G771-E) or RS232 DB9 plus 3.0 V TTL (7S1-E), USB 2.0 on all three, baud rates of 1,200 to 230,400 (460,800 on the module), a 1.8/3 V SIM slot, SMA female or IPEX antenna connectors, 9-36 V input (3.6-4.2 V or 5-16 V on the module), power below 3 W, operating temperature of -30 to +75 °C, and dimensions of 44.5 × 31.8 × 13.94 mm and 82.6 × 86 × 25 mm for the two modems. In software it lists TCP/UDP/IPv4/IPv6/DNS/HTTP/MQTT with SSL/TLS, four serial-to-network sockets, SMS in PDU or text, configuration by serial, network or SMS AT commands, remote FOTA upgrade, and packet framing by time (10-500 ms) or length (5-65,535 bytes). [1]

Wlink describes its D80 series serial-to-IP modem, "also named DTU", with PPP, TCP/IP and DDP protocols to convert RS232/485/422 serial data into IP data sent to a data centre over GPRS, 3G or 4G, and an industrial 4G/3G/2G modem with RS232, RS-485 and USB 2.0 that provides SMS and dial-up functions. [2]

03

USR LTE Cat 1 modems and Wlink DTUs

USR IoT publishes LTE Cat 1 modems and a module with full radio, serial and power data. Wlink Technology lists serial-to-IP DTUs and industrial cellular modems. Ask for band support, operator approvals, serial and protocol settings, and temperature test data.

04

Radio, SIM holder, antenna port, host port and firmware

What separates a modem from a solder-down module is everything around the radio: SIM slot, antenna connector, power input and a ready serial or USB port.

05

Bands, transmit power, sensitivity, host port and supply for LTE Cat 1 modems

The radio rows come from one LTE Cat 1 family; check the band list against your operator before comparing power and sensitivity.

06

Send network, host and installation data together

Paste it into your enquiry below or into an email to a maker, then replace every bracket.

Network: [countries; operators; bands; category; fallback]
Host: [port; baud; data format]
Protocol: [transparent; TCP/UDP; MQTT; PPP; SMS]
Power: [supply; consumption]
Installation: [housing; mounting; antenna; temperature]
Certification: [CE; operator approvals]
Quantity: [units]

See manufacturer records Send an enquiry through CNFX