DeviceNet and SDS Presented by : Ramesh Vishwanathan Biosystems and Agl. Engineering

Goals Introduction Introduction DeviceNet DeviceNet Smart Distributed Systems Smart Distributed Systems Comparison of DeviceNet and SDS Comparison of DeviceNet and SDS

Introduction An analogy – An analogy –  The Functionalities provided by CAN is similar to Latin letters in human communication.  To specify a language we need a stock of words as well as grammar to build sentences. CAN users specify their own CAN-based language, or the user decides to use a standardized CAN-based higher-layer protocol CAN users specify their own CAN-based language, or the user decides to use a standardized CAN-based higher-layer protocol Examples of CAN-based higher layer protocols are CANopen, DeviceNet, CANKingdom, SDC, etc. Examples of CAN-based higher layer protocols are CANopen, DeviceNet, CANKingdom, SDC, etc.CANopenDeviceNetCANKingdomCANopenDeviceNetCANKingdom

DeviceNet DeviceNet is an application layer protocol based on CAN 2.0A and is widely used in industrial automation DeviceNet is an application layer protocol based on CAN 2.0A and is widely used in industrial automation Originally developed by Rockwell / Allen- Bradley and is now an “open field” bus regulated by ODVA (Open DeviceNet Vendors Association) Originally developed by Rockwell / Allen- Bradley and is now an “open field” bus regulated by ODVA (Open DeviceNet Vendors Association) It is an “open”, low level network that provides connections between simple industrial devices (such as sensors and actuators) to higher-level devices (such as PLC controllers and computers) It is an “open”, low level network that provides connections between simple industrial devices (such as sensors and actuators) to higher-level devices (such as PLC controllers and computers)  DeviceNet

DeviceNet It uses a trunk line/drop line topology that provides separate twisted pair busses for both signal and power distribution which significantly reduces the amount of hardcore wiring It uses a trunk line/drop line topology that provides separate twisted pair busses for both signal and power distribution which significantly reduces the amount of hardcore wiring

DeviceNet This network allows a maximum of 64 logical nodes and supports 125, 250 and 500 Kbits/second data transfer rates This network allows a maximum of 64 logical nodes and supports 125, 250 and 500 Kbits/second data transfer rates Each module is assigned some priorities/IDs, which are a function of the node number (called MAC ID) and should be unique to avoid CAN specification violation Each module is assigned some priorities/IDs, which are a function of the node number (called MAC ID) and should be unique to avoid CAN specification violation Selectable end-to-end network distance varies with speed Selectable end-to-end network distance varies with speed  125 Kbps 500 m (1,640 ft)  250 Kbps 250 m (820 ft)  500 Kbps 100 m (328 ft)

DeviceNet Devices can be interfaced with network without removing power Devices can be interfaced with network without removing power Supports only Standard CAN Supports only Standard CAN Uses production/consumption model for module to module transfer Uses production/consumption model for module to module transfer Peer-to-Peer with Multi-Cast (one-to- many); Multi-Master and Master/Slave Polled or change-of-state Peer-to-Peer with Multi-Cast (one-to- many); Multi-Master and Master/Slave Polled or change-of-state

Components of DeviceNet Device

DeviceNet Each of these components are organized into attributes, services (methods or procedures), and behaviors of the components Each of these components are organized into attributes, services (methods or procedures), and behaviors of the components These objects are defined by DeviceNet specification. For instance, the identity object has attributes such as vendor ID, device type, and serial number. These objects are defined by DeviceNet specification. For instance, the identity object has attributes such as vendor ID, device type, and serial number.

DeviceNet A device profile consists of A device profile consists of device’s object model, device’s object model, I/O data format (including definition of assembly object(s) for efficient data transfer and, I/O data format (including definition of assembly object(s) for efficient data transfer and, the device’s configurable parameters documented in electronic data sheet (EDS ) the device’s configurable parameters documented in electronic data sheet (EDS )

Smart Distributed Systems (SDS) Developed by Honeywell's MICRO SWITCH Division Developed by Honeywell's MICRO SWITCH Division is also an advanced CAN based device- level communication network bus system for intelligent sensors and actuators is also an advanced CAN based device- level communication network bus system for intelligent sensors and actuators The SDS Application Layer Protocol is optimized for “Smart Sensors and Actuators”, where Configuration, Diagnostic, and Process information can be embedded cost-effectively in a very small footprint The SDS Application Layer Protocol is optimized for “Smart Sensors and Actuators”, where Configuration, Diagnostic, and Process information can be embedded cost-effectively in a very small footprint

Features of SDS Communication bit transfer rates are 125, 250, 500, and 1,000 kBaud Communication bit transfer rates are 125, 250, 500, and 1,000 kBaud 1500 ft maximum distance at 125 kBaud (longer with Bridge) 1500 ft maximum distance at 125 kBaud (longer with Bridge) Maximum of 125 modules can be connected to the network Maximum of 125 modules can be connected to the network 12-24VDC, 2 power wires + 2 communication wires + shield 12-24VDC, 2 power wires + 2 communication wires + shield 126 logical addresses - not related to physical location on the network 126 logical addresses - not related to physical location on the network Event-Driven, Master-Slave, Multicast and Peer to Peer Services Event-Driven, Master-Slave, Multicast and Peer to Peer Services

Example Use of SDS interface with state of art sensors Temp. A/D SDS Substrate RJ45 Press. A/D SDS Substrate RJ45 Substrate

SDS Small and effective way to connect small devices to a master controller. Small and effective way to connect small devices to a master controller. Master has 100% control of all modules. Master has 100% control of all modules. No support for communication between modules without a master PLC. No support for communication between modules without a master PLC. Supports only Standard CAN. Supports only Standard CAN. Effective when it comes to connect I/O devices (e.g., on/off switches, proximity sensors, etc.) to a PLC, as SDS fundamentally is a point to point communication between a master (Host) and remote I/O’s. Effective when it comes to connect I/O devices (e.g., on/off switches, proximity sensors, etc.) to a PLC, as SDS fundamentally is a point to point communication between a master (Host) and remote I/O’s.

SDS SDS has 2 Special APDU (Application Layer Protocol Data Unit) Forms:   Short Form APDU - Shortens the CAN message for single-bit commands such as COS, Write, and Acknowledgement. This allows for greater throughput and improved system response time.   Fragmented APDU - Allows for data messages longer than the standard 6 data byte format. Up to 256 bytes of data may be sent. This allows complex data such as ASCII strings to be sent across the network

Comparison SDSDeviceNet Possible bit rates 125k, 250k, 500k, 1M 125k, 250k, 500k Protection against modules with incorrect bit rate Yes.No Possible node numbers Default node number 12563

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