4G and the backup SIM

Every gateway has one backup SIM. It is already in the gateway, and ModbusCloud activates it before shipping. You do not need to insert or activate the SIM. You only connect the 4G antenna yourself.

When the gateway sends over 4G

The network cable in the WAN port has priority, as long as that network provides internet. The gateway checks this by itself. The table shows which connection it sends over in each situation.

If internet returns on the cable, the gateway switches back to the cable by itself. At a location without a network, leave the WAN port empty. The gateway then works entirely over the SIM. How to connect the cable is described in Connect to the network via WAN and LAN.

If the cable provides no internet and there is no 4G reception either, the gateway sends nothing and goes Offline. What to do then is described in Gateway is offline.

How often the gateway reads over 4G

Over the cable, the gateway reads each Modbus device at its own polling interval, from 1 second. Over the SIM, it never reads faster than the SIM interval. This is 300 seconds (5 minutes) by default and can go down to 60 seconds. A Modbus device with a longer polling interval keeps its own interval.

At each change of connection, the gateway switches between these intervals by itself. You do not need to do anything in the portal.

The SIM interval is one of the Gateway settings and applies to all Modbus devices on the gateway. How to change it is described in Choose the polling interval. If values arrive less often than you expect, see Values arrive less often than set.

Read the connection of the gateway

The portal shows for each gateway whether it currently sends over the cable or over the SIM. You see the pencil that opens the settings if you are an owner, administrator or technician.

1. Open the gateway

   Open the gateway.

2. Open the settings

   Click the pencil at the top right (Gateway settings).

3. Read the connection

   Look under Uitlezen via de SIM (reading via the SIM) at Verstuurt nu via (sending now via). It shows Kabel (cable) or SIM, with the date and time since when the gateway has sent over that connection.

The block Uitlezen via de SIM does not refresh by itself. Reload the page to see a new change.

If it shows Onbekend (unknown), the gateway has not yet reported which connection it sends over. A gateway with older software never reports this. On 4G it does not switch to the SIM interval and never reads more often than once every 60 seconds, also over the cable.

Place the antenna

Screw every supplied 4G antenna onto the gateway, even if there is a network cable in the WAN port. If that network fails, the SIM needs the antenna to take over.

A metal cabinet blocks the 4G signal. If the gateway is in a metal cabinet, place the antenna outside the cabinet.

Check the backup over 4G

You check whether the gateway can send over 4G at its location by letting it work for a moment without a network cable. The portal does not show the strength of the 4G signal. Start with a gateway that shows Kabel at Verstuurt nu via.

1. Unplug the cable

   Pull the network cable out of the WAN port of the gateway.

2. Wait for the change

   Reload Gateway settings until Verstuurt nu via shows SIM.

3. Plug the cable back in

   Plug the network cable back into the WAN port.

4. Check the return

   Reload Gateway settings until it shows Kabel again.

If it keeps showing Kabel and the gateway goes Offline, it does not send over 4G at that location. Plug the network cable back in and find the cause with Gateway is offline.

Data use over the SIM

Every reading that the gateway sends over the SIM uses 4G data. This is about 150 bytes per register, plus the connection to the portal. Monthly use depends mostly on the SIM interval, the number of registers and how long the gateway sends over the SIM. The amounts and the use per SIM interval are in 4G data and costs.

Automatic search also works when the gateway sends over 4G. The Modbus requests then go over the RS485 bus and the LAN port, not over the SIM. Only the progress and the results go over the SIM. This costs an estimated 26 to 43 kB per search, plus a few kB for each Modbus device found.

The gateway gives equipment on its LAN port no internet. A laptop on that port therefore uses no 4G data.