User's Manual

CHAPTER2
InstallingtheRTU
9
OperatingtheA753
The two ways to operate your A753 GSM/GPRS RTU are as follows:
1. GSM mode: You must ensure that your provider offers CSD
connections.
Most cellular/GSM providers use a different telephone number for
data communication than for voice communication. Don’t forget
to ask for this data number when you order your SIM card,
if you plan to use the RTU in GSM mode.
When your modem calls the RTU from a land line, it must use the
data number. If the modem uses the voice number, the RTU will
answer but will immediately send a busy tone, because the voice
line cannot make a data connection. Voice calls cannot
connect to a data terminal, so be sure to set up your
modem to use the data number when calling the RTU from
a land line.
2. GPRS mode: You must ensure that your SIM card is well suited
for GPRS operation.
InsertingtheSIMCard
You also need to insert that cellular provider's SIM card into the
A753GSM/GPRS RTU’s SIM card holder by following these steps:
1. Open the lid of the A753 by unscrewing the four bolt screws in
the corners of the unit and removing the lid as shown in Figure 2.
Make sure to use a 3mm Allen key to prevent damage to the
screw heads.
Figure 2. Lift the A753 lid
Note: You don’t have to remove the battery plug from the base board during
this operation, but make sure nothing is attached to the POWER
connector.