User's Manual

Using the A73x RTU

2.3 Special notes for the A733GSM RTU

The A733GSM RTU is based on a GSM module which employs a GSM cellular

network to transmit the telemetry data. Before you install such a device you must

make sure that there is sufficient signal for proper operation of the RTU on the site

you plan to use it; this is done best by using a standard cellular phone operated by

the same cellular provider. You can also check if you can communicate with the

RTU simply by calling it as a normal cellular phone.

Most cellular/GSM providers use a different telephone number for data

communication than for voice communication. Don’t forget to ask for it when

you order your SIM card!

When you call the RTU from a standard phone, use the data number: else the RTU

will answer, but immediately send a busy tone, as the voice call cannot connect to

a data terminal.

In addition you need to insert your SIM card into the SIM-holder inside your

A733GSM RTU. This is done as follows:

1. Open the lid of the A733GSM RTU by unscrewing the four bolts in the corners

of the RTU, then remove the lid as shown in Figure 3 .

Fig. 3: Removing the A73x Lid

Note: It is not required to remove the battery plug from the base board during this

operation, but make sure nothing is attached to the POWER connector!

Fig. 4: Installing the SIM card in the A733GSM RTU

2. Locate the SIM card holder and open it by sliding it as indicated by the red

arrow (see Fig. 4, left).