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Quectel RG255C-GL 5G RedCap

Quectel RG255C-GL is a compact, industrial-grade 5G RedCap module designed for mid-tier IoT applications. It supports 5G NR (SA) with LTE fallback, delivering download speeds up to 223 Mbps and upload up to 123 Mbps. The module offers global band support, integrated GNSS (GPS, GLONASS, Galileo, BeiDou, NavIC), and features ultra-low power consumption. Available in LGA, M.2, and Mini PCIe form factors, it supports a wide range of interfaces and is ideal for energy-efficient, reliable 5G connectivity across diverse devices.

Quectel RG255C-GL 5G RedCap

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Prerequisites

  • Monogoto SIM

  • Quectel RG255C-GL 5G RedCap cellular modem

  • Access to a private network

Connect the RG255C-GL 5G RedCap to Monogoto

When connecting to the RG255C-GL 5G RedCap modem, keep the AT Commands manual next to you to look up details about commands.

Connect to the modem, enter the command: AT and wait for the response: OK

When using Windows, install the driver using the disk or USB stick provided by Simcom.

Reset the modem to the factory default configuration:

AT+CFUN=1,1

Set the error reporting to verbose, resulting in more descriptive error messages (optional):

AT+CMEE=2

Check if the SIM card is attached and is not locked with a PIN, expected response: +CPIN: READY:

AT+CPIN?

If you receive an error, the SIM may not be inserted properly or the SIM is protected with a PIN. By default, Monogoto SIMs are not PIN protected.

Query device information

Request the modem hardware version:

AT+CGMM

Request the modem firmware version:

AT+CGMR

response:

+CGMR: RG255CGLABR01A04M4G_BETA250513A

Request the IMSI (International Mobile Subscriber Identity):

AT+CIMI

Request the ICCID (Integrated Circuit Card ID), which is the identification number of the SIM card

AT+ICCID

Network mode preference.

Manually set the preference mode:

  • AT+QNWPREFCFG="mode_pref",LTE:NR5G → Enables 5G NR along with LTE, UMTS, and GSM (multi-mode operation).

  • AT+QNWPREFCFG="mode_pref",LTE → Typically enables LTE/UMTS/GSM only (no 5G).

To test if the network is set correctly enter:

AT+QNWPREFCFG="mode_pref"

Expected response: +QNWPREFCFG: "mode_pref",AUTO

Network Configuration

Manually set the network:

Monogoto's private LTE network is indicated with the MCCMNC code: 99974. To connect to the private LTE network, enter:

AT+COPS=1,2,"99974",11

To test if the network is set correctly enter:

AT+COPS?

Expected response: +COPS: 0,0,"Monogoto5G 99974",11

11 indicates that the modem is using 5G SA.

Check the radio signal strength and signal quality:

AT+CSQ

Example response: +CSQ: 22,1

+CSQ returns 2 values separated by a comma. The first value represents the signal strength and provides a value between 0 and 31; a higher number indicates better signal strength. The second value represents the signal quality indicated by a value between 0 and 7, a lower value indicates better signal quality . If AT+CSQ returns 99,99, the signal is undetectable or unknown.

Network Activation

Set the APN to data.mono:

AT+CGDCONT=1,"IP","data.mono"

To test if the APN is set correctly, enter:

AT+CGDCONT?

Expected response: +CGDCONT: 1,"IP","data.mono","0.0.0.0",0,0,0

Activate the PDP (packet data protocol) context:

AT+CGACT=1,1

Test if the PDP context is activated:

AT+CGACT?

Expected response: +CGACT: 1,1

Request Serving Cell Information

AT+QENG="servingcell"

Example response:

+QENG: "servingcell","NOCONN","NR5G-SA","TDD",999,74,000004001,5,2,638592,78,3,-66,-10,28,1,49

  • 99974 (the fourth value) indicates that the device being connected to Monogoto's Private LTE Network

  • 78 represents the cellular band the modem is currently using

Validate if your device received an IP address:

AT+CGPADDR

Expected response: +CGPADDR: 1,10.XXX.XX.XXX

Test the connection by sending a PING

A PING test can be performed to test if the modem has an active data connection with a mobile network.

When cellular modems are idle for a long period of time, cell towers might drop the data connection to save resources. Sending regular PINGs is a good method for testing the data connection, as well as for keeping the connection alive because the operator registers your device as being actively used.

Send 4 PINGs to IP address 8.8.8.8:

AT+QPING=1,"8.8.8.8",4

Example response:

+QPING: 0,"8.8.8.8",32,16,255
+QPING: 0,"8.8.8.8",32,14,255
+QPING: 0,"8.8.8.8",32,15,255
+QPING: 0,"8.8.8.8",32,17,255

Do you see an IP address? Congratulations! 🎉 You’ve successfully connected the Quectel RG255C-GL 5G RedCap to Monogoto. Have a look at the Things logs in the Monogoto Console to find more details about the established connection.

Useful Links

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