科隆流量计modbus通讯手册

IFC 300

Supplementary Handbook

Signal converter with

Modbus interface for OPTIFLUX electromagnetic flowmeters

Modbus ER 3.2.xx ( SW.REV.3.2.x )

Modbus version 1.1.x

Subject to change without notice.

KROHNE 09 / 2008

IFC 300 Modbus

Content

1 Important

information 3 2 Technical

data 3

3 Connection of instruments in bus system 4

4 Electrical

connection 4 5 Modbus protocol 5 – 16 5.1 General 5 5.2 RTU Frame format 5 5.3 Overview of supported function 6 5.4 Device identification on the Modbus interface 6 5.5 Coil

registers 7 5.5.1 GDC Controls 7 5.5.2 Start calibration function 7 5.5.3 Counter controls 7 5.6 Input

registers 8 5.7 Holding registers 9 – 12 5.7.1 Counter parameters 9 – 10 5.7.2 Process input filter parameters 11 – 12 5.7.3 Modbus parameters 12 5.8 Calibration procedures 13 – 15 5.8.1 Zero flow calibration 13 5.8.2 Coil temperature calibration 14 5.8.3 Conductivity calibration 15

5.9 Diagnostics 16

6 Form (for copying) to accompany a returned instrument 19 1 Important

information

The flow converter with the RS 485 interface card fitted, is able to communicate with an external device (PC or other suitable computer system) using the Modbus protocol. This option allows data exchange between PC or computer and single or multiple devices.

The bus configuration consists of one external device as a master and one or more converters as slaves. For bus operation the device address (menu C5.8.1), baud rate (menu C5.8.2) and settings (menu C5.8.3, C5.8.4 & C5.8.5) must be set in the converter. All devices connected to the bus, must have different unique addresses but the same baud rate and settings.

2 Technical

data

Interface RS 485, galvanically isolated

Baud rate 1200, 2400, 4800, 9600, 19200, 38400, 57600 or

115200 baud

Protocol Modbus

RTU

(available as a separate document on request) Maximum participants on Bus 32 per line, master included

(may be extended by repeaters)

Coding NRZ bit coding

Address range Modbus: 1 (247)

Transmission procedure Half duplex, asynchronous

Bus access Master / slave

Cable Screened twisted pair cable

Distances Maximum 1.2 km without repeater.

(dependant on baud rate and cable specifications)

Technical data of the Modbus interface (according to EIA standards)

Kind of signal transmission Differential

Maximum number of transmitter/receivers 32

Maximum voltage on driver output -7 … +12 V

Minimum voltage on driver output, max. load U diff > 1,5 V

Maximum input current (off state) -20 … +20 µA

Receiver input voltage -7 V … +12 V

Sensitivity of the receiver -200 … +200 mV

Receiver input resistance > 12 kOhm

Short circuit current of transmission < 250 mA