Grundfos CIU 501 Instructions

English (GB)
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12. Detailed descriptions of functionality
12.1 GSM
12.1.1 Call-up functional description
The call-up function is used for SCADA system communication
via the GSM network. Connection is established when the
SCADA system dials the CIU 250. The CIU 250 will automatically
"pick up the phone" and wait for data traffic in the form of Modbus
RTU telegrams.
If legal data traffic has not been initiated within one minute, the
CIU 250 will hang up the line. This silence timeout is active during
the whole communication session. Whenever the SCADA system
has completed the Modbus communication, it hangs up the line.
This is detected by the CIU 250, which also hangs up the line,
and the call-up communication session is thereby completed.
See fig. 24.
Fig. 24 Illustration of a GSM call-up session
12.1.2 SCADA PIN code protection
It is always possible to get read access via Modbus, but if the
CIU 250 is SCADA PIN-code-protected (GeneralStatus register
00029, bit 0 = 1), write access requires that the correct PIN code
(ScadaPinCode, register 00011) has been written. Writing the
correct PIN code will trigger the write access control, and write
access will be open, which can be verified with GeneralStatus,
register 00029, bit 1 = 1).
For call-up connections with PIN code protection, the
ScadaPinCode register has to be written each time a new call-up
is made.
12.1.3 GSM call-up options setup
To prepare the CIU 250 for Modbus communication with a
SCADA system via GSM, some settings have to be made via
SMS commands:
• Setting a SCADA PIN code:
SETSCADACODE <access code> will enable write access
protection.
Default is an empty SCADA PIN code, meaning no protection.
• Activating the SCADA PIN code:
SCADACODE <ON | OFF>.
Default is "Off".
• Selecting the Modbus address:
MODBUSADDR <1-247>
Default value is 231.
To verify the SCADA GSM setting after completion, the SMS
command "SCADA" can be used.
For details about the use of SMS commands, see "CIM 25X SMS
commands" (supplement to the installation and operating
instructions) on the CD-ROM supplied with the GSM module.
12.2 GPRS
12.2.1 What is GPRS and Modbus TCP?
GPRS (General Packet Radio Service) is a wireless, "always on"
connection that remains active as long as the CIU 250 is within
range of the service. With GPRS it is possible to establish a
wireless connection to the Internet and thus enable a remote
connection to a SCADA system computer or another PC
application. Typical data rates are 32 to 48 kbit/s.
The GPRS itself takes care of the wireless data transfer via the
GSM network. It plays the same role as Ethernet in a wired
network. On top of GPRS is the TCP/IP protocol, which enables
easy integration with the Internet. The Modbus TCP protocol is
used on the application layer communicating with a TCP port
number (default 502). The difference when compared to the
fieldbus protocol Modbus RTU is the exclusion of the 16-bit CRC
checksum and the adding of a Modbus application program
header as illustrated in fig. 25.
TM04 4905 2209
Dialling
Connection established
Hang-up
Modbus communication
Silence timeout after 1 min
without communication
GSM network,
e.g. SCADA
CIU 250
Hangs.
Hangs up.
Session
completed.

Grundfos CIU 501 Specifications

General

Brand	Grundfos
Model	CIU 501
Category	Controller
Language	English