Bronkhorst DeviceNet slave interface - Manual (Page 11)

BRONKHORST ®
Page 11 DeviceNet interface 9.17.026
3 FUNCTIONAL DESCRIPTION
3.1 G ENERAL
The Bronkhorst digital instruments will behave as slaves on the DeviceNet bus. This means all communication
(instructions / readout) will be performed by a master on the same DeviceNet field bus. Mostly this will be any PLC or
PC‐card controlling a process.
The Bronkhorst DeviceNet MFC is a Group 2 Only Server device which messages comply with the CAN 2.0A standard
and with the DeviceNet protocol. The DeviceNet MFC supports two types of connection: Explicit and Polled I/O. As
defined by the DeviceNet protocol.
3.2 O
BJECTS AND SERVICES
Bronkhorst MFC’s consist of several objects with attributes and services for interfacing to DeviceNet. These objects
are described below.
The DeviceNet Mass Flow Controller will be in "Idle" state after powered on or reset. In this state, the device will not
allow the Master to use the Setpoint Attribute to control gas flow. Instead, gas flow will be controlled by the value
previously set in the Analog Actuator Object’s Safe‐State Attribute and Safe‐Value Attribute. For instance, if the Safe‐
State Attribute had a value 0x03 which is the code for “Use Safe Value” then the device will set the actuator (valve)
according to the value previously stored in the Analog Actuator Object’s Safe‐Value Attribute. To be able to control
the flow, the Master device must send a “Start” request to the supervisor object of the Mass Flow Controller. The
“Start” request brings the device from “Idle” state to “Executing” state. In this state, the device will be executing new
setpoints received from the Master and then control the flow accordingly. Another way to bring the device in the
"Executing" state is by sending I/O data (Polled I/O).
3.3 E XPLICIT MESSAGING
Using explicit messaging, following tables are needed with the descriptions of DeviceNet objects for Digital Mass Flow
/ Pressure Controllers / Meters. These messages have an a‐cyclic character. For cyclic messages, see Polled I/O in the
next paragraph.
The FLOW‐BUS column shows how DeviceNet attributes are mapped on the internal FLOW‐BUS
variables of the instrument. This information can be useful for who is familiar with FLOW‐BUS.
3.3.1 Identity Object
Class Code: 01 HEX
This object provides identification of and general information about the device. The Identity Object is present in all CIP
products.
IDENTITY OBJECT’S INSTANCE ATTRIBUTES (Instance = 1)
IDENTITY
OBJECT
ATTRI‐
BUTE
ATTRIBUTE NAME
SERVICE
CODE
DATA TYPE
FLOW‐
BUS
Comment
0x01 0x01 Vendor Id 0x0E UINT 706
0x01 0x02 Device Type 0x0E UINT 0x001A
0x01 0x03 Product Code 0x0E UINT 113,12 IdentNr
0x01 0x04 Revision 0x0E STRUCT V major. minor
0x01 0x05 Status 0x0E WORD always 0x0001
0x01 0x06 Serial Number 0x0E UDINT calculate from 113,3
0x01 0x07 Product Name 0x0E SHORT‐STRING “Bronkhorst meter/controller”