Bray 70 Series SERVO PRO DeviceNET - Manual (Page 17)

S70 DeviceNet Servo Installation & Maintenance Manual
2000 BRAY CONTROLS Page 16 of 24
When adding devices to a network, it is best to setup an independent workstation with a
DeviceNet interface for Node Commissioning. Any Node Commissioning application can be
used to configure the S70 Servo. Refer to the application software user manual for specific
information on Node Commissioning.
3.3 Communication
All communication with the S70 Servo takes place over the DeviceNet network. The DeviceNet
interface gives the user the ability to control and monitor the S70 Servo and S70 Actuator.
The S70 Servo supports standard DeviceNet Polled and Explicit messaging connections.
3.3.1 Polled Message Connection
A polled message connection provides a Master with the ability to rapidly send and receive
short messages to all
devices on a network in a “polled” fashion. This is typically the main
communication mode of a process controller.
The Polled message sent by the master must by 2 bytes and corresponds to a requested valve
position. The S70 Servo responds with 2 bytes, which corresponds to the current valve
position.
The range for valid data is “0” to “0x7FFF” which represents a “0°” to “90°” valve position.
3.3.2 Explicit Message Connection
An explicit message connection provides the Master with the ability to directly access a
particular parameter that is supported by the S70 Servo. These parameters are accessed by
using the “GET” or “SET” DeviceNet attribute service. As an example, an Explicit Message can
be used to position the valve, monitor the motor temperature, and set special features. Refer to
Section (3.1.6) for further information.
3.4 EDS (Electronic Data Sheet)
An EDS (Electronic Data Sheet) is an external file that contains information about configurable
attributes for a device, including object addresses of each parameter. The EDS provides the
user with a simple to use interface for configuring and monitoring a device.
Many software applications access the EDS file, which is included with the S70 Servo to aide in
the configuration of the network, and the devices on the network. Products such as the process
controller will use the EDS to automatically obtain the data that is required for configuration.
Refer to Figure 6 for an example of how an application uses the EDS information to create a
graphical display of a network.