MKS Granville-Phillips Mini-Convectron 275 series - DeviceNet Protocol and Communication

5 DeviceNet Operation
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Series 275 Mini-Convectron Module with DeviceNet
Instruction Manual - 275563
The DeviceNet protocol conveys two types of messages, as defined in Table. Once the
Mini-Convectron Module is operating, use the polled I/O or explicit messages to perform the tasks
listed in Table 5-3.
8. Configure the expected packet rate for the explicit and polled connections, as listed in Table
5-4. The default explicit message expected packet rate is 2.5 seconds. If data is requested as a
slower rate, this must change to prevent the connection from expiring. See Table 5-4 to disable
the expected packet rate.
5.1.1 DeviceNet Protocol and Communication
The DeviceNet protocol used for the Mini-Convectron Module is based on the Open DeviceNet
Vendors Association (ODVA) and S-Analog Sensor Object Class Subclass 01 (Instance Selector)
standards. The command set includes public and vendor-specific classes, services, and attributes.
DeviceNet communication requires identifier fields for the data. The use of identifier fields provides
the means for multiple priority levels, efficient transfer of I/O data, and multiple consumers. As a
node in the network, the module produces data on the network with a unique address. All devices
on the network that need the data listen for messages. When other devices on the network recognize
the module’s unique address, they use the data.
Note: Unsigned binary is used to represent the pressure.
Table 5-3 Network Master Connection
Message Type Message Purpose
Polled I/O messages
• Used for time-critical, control-oriented data.
• Provides a dedicated, special purpose communication path between a producing
application and one or more consuming applications.
Explicit messages
Provides multipurpose, point-to-point communication paths between two devices.
Provides typical request/response oriented network communications used for
performing node configuration and problem diagnosis.
Table 5-4 Disabling the Expected Packet Rate
Parameter Service Class Instance Attribute Data
Service 10
hex
51* 9 0
*Instance: 1 = Explicit connection, 2 = Polled Connection
Table 5-5 Polled I/O Messaging Summary
Instance Master data Device data Data type Description Typ e
1 None 00 00 UINT UINT vacuum pressure Open