Owner manual

2424 Visit our Web Site www.n-c.com
IntellIsys AdAptIve pressure Controllers
APC-OP-LIT 1/12
8.2 - Establishing a DeviceNet connection
This section describes how to communicate and control the IQD using the DeviceNet port. DeviceNet has two basic message types: Explicit and I/O messaging.
How to get device identity information:
• Select the service code 0E (get attribute)
• Select class ID 1 (select the identity object)
• Select instance ID 1 (there is only instance supported)
• Select attribute ID 1 (vendor ID attribute)
• The device will respond with data bytes 64 02 meaning 264hex
or 612dec, which is the vendor ID that has been attributed to
Nor-Cal Products Inc.
• Change the attribute ID for 6 (serial number attribute)
• The device will respond with data bytes, 3A B1 02 00 meaning
2B13Ahex or 176442dec, which is the serial number of the device.
(Nor-Cal device serial numbers are composed of 6 digits)
How to control valve position:
• Select the service code 10 (set attribute)
• Select class ID 2E (select the selection object)
• Select instance ID 1 (setpoint)
• Select attribute ID 5 (destination index) followed by the data 02.
This puts the destination index to the value 2 having for effect
to select valve position control
then . . .
• Select the service code 10 (set attribute)
• Select class ID 2E (select the selection object)
• Select instance ID 1 (setpoint)
• Select attribute ID 9 (source data value) followed by the setpoint 00 40
• The device will move the valve to 50% of it’s stroke(45º angle)
• Select attribute ID 9 (source data value) followed by the
setpoint 00 00 The device will move the valve to 0% of its
the stroke or closed
How to read the valve limit switch
• Select the service code 0E (get attribute)
• Select class ID 8 (select the selection object)
• Select instance ID 1 (closed limit switch)
• Select attribute ID 3
• The device will respond with data bytes 01 meaning that
the closed limit switch is activated and the valve is closed
• Select instance ID 2 (open limit switch)
• Select attribute ID 3
• The device will respond with data bytes 00 meaning that
the open limit switch is not activated and the valve is not opened
Explicit Messaging:
Explicit messages are used to read or write an individual piece of information
in the device. They are mainly used for initial configuration. Explicit messages
include the path to locate the data of interest, this consists of the class ID,
attribute ID, and instance number. They also specify an action to be taken.
The table below lists some of the key information available through explicit
messaging. Please refer to Section 9 for the full device profile characteristic.
TABLE 8.3 - DEVICENET EXPLICIT MESSAGING
CLASS
ID
INSTANCE
ID
ATTRIBUTE
ID ACTION
VARIABLE
NAME
1 1 1
0E (get) Vendor ID
1 1 6 0E (get) Serial Number
1 1 7 0E (get) Product Name
3 1 1 0E (get) 10 (set) MACID
3 1 2 0E (get) 10 (set) Baud Rate
31 1 6 0E (get)
Process input
(CDG1)
31 2 6 0E (get)
Process input
(CDG2)
31 3 6 0E (get) Valve position
2E 1 5 0E (get) 10 (set)
Pressure control
and position
control
2E 1 9 0E (get) 10 (set) Process setpoint
The most straightforward way of sending individual commands to the
controller is to use a node-commissioning software utility. These utilities
are part of the DeviceNet interface card package.
Explicit messaging connection examples:
• Power up the device, the network LED will transition to flashing green
• Let the master open an explicit connection with the device
• The network LED will transition to solid green
As a reminder, note that data to and from the device is always encoded least
significant byte first as specified in the data management section of the
DeviceNet protocol specification. For instance the value 12345678hex
is encoded as follow:
OCTET NUMBER
1st 2nd 3rd 4th
OUTPUT DATA
78 56 34 12