Notes on configuration and operation
5.2 Connection modes and connection establishment
CP 1242-7 V2
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Operating Instructions, 05/2014, C79000-G8976-C311-00
GPRS direct
This mode of the CP is used for direct communication between remote stations via the
GSM network. No telecontrol server is necessary.
To allow network nodes in public wireless networks to be directly accessible, these need
to be addressed using a fixed address. Here, SIM cards with a fixed IP address are used
that allow the stations to address each other directly.
The possible communications services and security functions (for example VPN) depend
on what is offered by the network provider.
Possible communications partners of the GPRS station with a CP 1242-7 GPRS V2 in
"GPRS direct" mode are:
–
A subscriber that can be reached by the CP via an IP address (for example S7-1200
with CP 1242-7 GPRS V2)
–
An engineering station (for TeleService)
5.2
Connection modes and connection establishment
Note
Connection interrupted by GSM network provider
When using the GPRS service, remember that existing connections can be interrupted by
GSM network providers for maintenance purposes.
Connection modes
"GPRS direct" mode
There are no different connection modes in the "GPRS direct" mode.
"Telecontrol" mode
The CP can be configured for the following connection modes.
–
"Permanent" connection mode
There is a permanent TCP connection to the telecontrol server. Following connection
establishment, there is a permanent TCP connection to the telecontrol server even if
data is not transferred permanently.
If a TCP connection is established, process data is sent as soon as the telecontrol
instructions are called on the CPU.
Connection establishment
A connection is always established by the CP. If a connection established by the CP is
interrupted, the CP automatically attempts to re-establish the connection.
