Instruction Manual

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IntellIsys AdAptIve pressure Controllers
IQ+ OP-LIT 9/08
7.2 - DeviceNet Communications
This section describes how to communicate with and control the controller using the DeviceNet port. DeviceNet has two basic message types: Explicit and I/O
How initialize the valve (not required on all valve types):
• S
elect the service code 32 (initialize service)
• Select class ID 30 (select the s-device supervisor object)
• S
elect instance ID 1
How to transition the controller to the executing state:
To be able to perform pressure or position control by means of explicit
messaging, the controller has to be transitioned to the device Executing state.
• S
elect the service code 6 (start service)
• S
elect class ID 30 (select the s-device supervisor object)
• S
elect instance ID 1
How to control valve position:
• S
elect the service code 10 (set attribute)
• S
elect class ID 2E (select the selection object)
• S
elect instance ID 1 (setpoint)
• S
elect attribute ID 0E (destination used) followed by the data 02 (position
control)
t
hen
• S
elect the service code 10 (set attribute)
• S
elect class ID 2E (select the selection object)
• S
elect instance ID 1 (setpoint)
• S
elect attribute ID 0F (source data value) followed by the setpoint 00 40
• T
he device will move the valve to 50% of its stroke
• S
elect attribute ID 0F (source data value) followed by the
setpoint 00 00 The device will move the valve to 0% of its
s
troke or closed
How to control pressure:
• Select the service code 10 (set attribute)
• S
elect class ID 2E (select the selection object)
• S
elect instance ID 1 (setpoint)
• S
elect attribute ID 0E (destination used) followed by 01 (pressure control)
then
• S
elect the service code 10 (set attribute)
• Select class ID 2E (select the selection object)
• S
elect instance ID 1 (setpoint)
• S
elect attribute ID 0F (source data value) followed by the setpoint 00 20
(
pressure control)
• T
he device will try to control pressure at 25% of full scale of the selected
p
ressure source
• S
elect attribute ID 0F (source data value) followed by the setpoint FF 7F
T
he device will try to control pressure at 100% of full scale of the selected
p
ressure source
How to read the valve limit switch:
• S
elect the service code 0E (get attribute)
• S
elect class ID 8 (select the discrete input point object)
• S
elect instance ID 1 (closed limit switch)
• S
elect attribute ID 3
• T
he device will respond with data bytes 01 meaning that
the close limit switch is activated and the valve is closed
• S
elect instance ID 2 (open limit switch)
• S
elect attribute ID 3
• T
he device will respond with data bytes 00 meaning that
the open limit switch is not activated and the valve is not opened
messaging
Explicit Me
ssaging:
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 7.3 - DEVICENET EXPLICIT MESSAGING
CLASS
ID
HEX
INSTANCE
ID
HEX
ATTRIBUTE
ID
HEX
SERVICE ID
HEX
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
(low range)
31 2 6 0E (get)
Process input
(high range)
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:
• P
ower up the device, the network LED will transition to flashing green
• L
et the master open an explicit connection with the device
• T
he network LED will transition to solid green
Note that in DeviceNet communications, data to and from the device is always
encoded least significant byte first as specified in the data management sec-
tion of the DeviceNet protocol specification. For instance the value 12345678
hex is encoded as follow:
OCTET NUMBER
1st 2nd 3rd 4th
OU
TPUT DATA
78 56 34 12
How to get device identity information:
• S
elect the service code 0E (get attribute)
• S
elect class ID 1 (select the identity object)
• S
elect instance ID 1 (there is only instance supported)
• S
elect attribute ID 1 (vendor ID attribute)
• T
he device will respond with data bytes 64 02 meaning 264 hex
or 612 dec, which is the vendor ID that has been attributed to
N
or-Cal Products Inc.
• C
hange the attribute ID for 6 (serial number attribute)
• T
he device will respond with data bytes on the form, 3A B1 02 00
meaning 2B13A hex or 176442 dec, which is the serial number of the
d
evice.
(
Nor-Cal device serial numbers are composed of at least 6 digits)
Note: The examples above assume that default data
type (INT) and data units (Counts) is used.