Modbus for Grundfos pumps

Modbus for Grundfos pumps The system diagrams provide an overview of the different technologies and how to connect the module or unit to the Grundfos E pump that you connect to a Modbus network.

With Modbus cards, the pumps can be controlled from the monitoring system (or from PLC), and all technical parameters are available from the units.

CIU solution

The Communication Interface Unit (CIU) is a box with a power supply module and a CIM Modbus module. You can mount either on a DIN rail or on a wall.
You use it in conjunction with Grundfos E-pumps that do not support an internal, add-on communication module, CIM.

CIM solution

Grundfos CIM 500 Modbus TCP The Communication Interface Module (CIM) is an add-on communication module you install internally in a Grundfos E-pump using a 10-pin connection. In this setup, the E-pump will supply power to CIM 200.
For mounting of the CIM add-on module, see the installation and operating instructions for the E-pump in question.

CIM 200 Modbus RTU

Modbus RTU specificationsDescriptionComments
Modbus connectorScrew-type terminal3 pins
Modbus connection typeRS-485, 2-wire + commonConductors: D0, D1 and Common
Maximum cable length1200 mEquals 4000 ft
Slave address1-247Set via rotary switches SW6 and SW7
Line terminationOn or OffSet via DIP switches SW1 and SW2
Recommended cable cross-section0.20 - 0.25 mm2AWG24 or AWG23
Supported transmission speeds1200 1), 2400 1), 4800 1),
9600, 19200, 38400 bit/s
Set via DIP switches SW4 and SW5
Start bit1Fixed value
Data bits8Fixed value
Stop bits1 or 2Set via DIP switch SW3
Parity bitEven parity, odd parity 1) or no paritySet via DIP switch SW3
Modbus visual diagnosticsLED1Off, flashing green, flashing red, permanently red
Maximum number of Modbus devices32Using repeaters, you can increase this number.Legal address range is 1-247
Maximum Modbus telegram size256 bytesTotal length. Node address and CRC included

Application example

Grundfos CIM 200 Modbus RTU application example

Through the CIM 200 module, the Grundfos pump can be controlled directly from the various controllers, and all its parameters can be read. These parameters can be displayed, for example, on HMI or SCADA. The Ethernet / RS485 converter converts TCP telegrams into RTU form and transmits them as such. Thanks to this unit, the connection can serve several master units (multimaster). The video below shows (and hears) the operation of the first Labview test program. This is just a test program I wrote to test the connection, not a particularly spectacular application.

First Labview testprogram for Grundfos CIM 200 modul

Related links:

CIM 260 3G/4G cellular Modbus

Modbus cellular specificationsDescriptionComments
Data protocolModbus TCPData connection uses Modbus TCP
Slave addressFactory 231 (0xE7)You can change the address via Modbus register 00003,
Cellular connection visual diagnosticsLED1
Maximum Modbus telegram size260 bytesTotal Modbus TCP/IP application data unit

CIM 500 Modbus TCP

Modbus TCP specificationsDescriptionComments
Application layerDHCP, HTTP, Ping, FTP, Modbus TCPRotary switch in position 1 to select Modbus TCP
Transport layerTCP
Internet layerInternet protocol V4 (IPv4)
Link layerARP, media access control (Ethernet)
Ethernet cableCAT5, CAT5e or CAT6Supports auto cable-crossover detecting (Auto-MDIX)
Maximum cable length100 metresCorresponds to 328 feet
Transmission speed10 Mbit/s, 100 Mbit/sAuto-detected

Application example

Grundfos CIM 500 Modbus TCP application example

Through the CIM 500 module, the Grundfos pump can be directly controlled from the S7-1500 PLC, and all its parameters can be read. These parameters can be displayed, for example, on HMI or SCADA.

Modbus structure (registers)

See it: Grundfos download Grundfos Modbus specification, 18 Mbyte

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