Grundfos CIU 501 User Manual

English (GB)
44
12. Detailed descriptions of call-up and APN
12.1 Call-up
12.1.1 Call-up functional description
The call-up function is used for SCADA system communication
via the cellular network. Connection is established when the
SCADA system dials CIU 260. CIU 260 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, CIU
260 will hang up the line. This silence time-out 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 CIU 260, which also hangs up the line, and the
call-up communication session is thereby completed. See fig. 31.
Fig. 31 Illustration of a call-up session
12.1.2 SCADA PIN code protection
It is always possible to get read access via Modbus, but if CIU
260 is SCADA PIN-code-protected (GeneralStatus register
00029, bit 0: 1), write access requires that the correct PIN code
(ScadaPinCode, register 00011) has been entered. Entering the
correct PIN code will trigger the write access control, and write
access will be open, which you can verify 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 Call-up options setup
To prepare CIU 260 for Modbus communication with a SCADA
system via a call-up connection, 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 setting: 231.
To verify the SCADA settings after completion, use the SMS
command "SCADA".
For details about the use of SMS commands, see "CIM 260 SMS
commands", which you can download from Grundfos Product
Center.
12.2 APN
12.2.1 What is APN and Modbus TCP?
An APN connection (Access Point Name) is a wireless, 'always
on' connection that remains active as long as CIU 260 is within
range of the service. With a data connection, 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.
The APN connection takes care of the wireless data transfer via
the cellular network. It plays the same role as Ethernet in a wired
network. We will refer to an APN connection as a data
connection, and it also makes use of 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. 32.
TM04 4905 2209
Dialling
Connection established
Hang-up
Modbus communication
Silence timeout after 1 min
without communication
Cellular network,
e.g. SCADA
CIU 260
Hangs up
the line.
Hangs up.
Session
completed.

Grundfos CIU 501 Specifications

General

Brand	Grundfos
Model	CIU 501
Category	Controller
Language	English