Question

Hi, 

I use a TRB255 with FW version TRB2_R_00_07_04.2.
If modem control is turned off the modem receives an IP address on interface "mob1s1a1" (Type:Mobile).

LEDs:
M1, turned on

If I enable Modem control (Full control) interface "mob1s1a1" goes down.

LEDs:
2G, NB and M1 LEDs are blinking at the same time

How can I configure the modem not to lose connection when enabling serial interface?

BR

Jonas

Answer 1

Hello,

When full modem control is enabled, interface "mob1s1a1" goes down, because the daemon, responsible for for handling mobile connection is disabled and modem serial port is connected directly to RS interface. Thus, mobile connection must be established manually by the use of AT commands.

You would need to use partial control setting in order to maintain mobile connection.

Best regards,

Comments

Hi,

Ok, when we use modem TRB142 we can disable serial interface and still have mobile connection.

What is the difference between the two modems?

BR

Jonas

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In theory, at least from my prior knowledge, neither of the devices should establish data connection, when operating in full modem control modem. However, I have just set up TRB245, running TRB2_R_00.07.04 (I do not have access to NB or M1 networks to test) and TRB142 with TRB1_R_00.07.04.1 and both devices did establish data connection.

I will consult about this, however, when in full modem modem control mode, no firmware services controlling modem functionality should work and all control, including data connection, should be carried out by the user.

Best regards,

---

Ok, which protocol should I use when setting up the interface of the TRB255? PPPoS is not an option. Should I select "Mobile". I want to set up a PPP channel between modem and our device and control the modem over RS232.

---

Mobile related pages become hidden and mobile interface is not configurable, when Full control mode is enabled.

There is an example, of how to set up PPP communication between a TRM240 (a feature stripped version of TRB, simply EC21 modem) and a Raspberry pi, provided here.

Otherwise, I suggest to refer to PPP application note from Quectel, which is provided here, and this Linux USB guide.

Best regards,   

---

Ok we use TRB142 for the european market, now we need a modem for the US market. Can TRM240 be used in the US?

TRB142 has a Quectel EC21 modem, right?

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TRM240 cannot be used in the US. None of the two available versions have a modem certified with many of the major US providers (Verizon, AT&T, T-Mobile).

For US operation, you would need to look at RUT2 or RUT9 series devices.

As for TRB142, it indeed has a Quectel EC21 modem.

Best regards,