DeviceNet and SDSDeviceNet and SDS

Presented by :Presented by :

Ramesh VishwanathanRamesh Vishwanathan

Biosystems and Agl. EngineeringBiosystems and Agl. Engineering

GoalsGoals

IntroductionIntroduction DeviceNetDeviceNet Smart Distributed SystemsSmart Distributed Systems Comparison of DeviceNet and Comparison of DeviceNet and

SDSSDS

IntroductionIntroduction

An analogy – An analogy – The Functionalities provided by CAN is The Functionalities provided by CAN is

similar to Latin letters in human similar to Latin letters in human communication.communication.

To specify a language we need a stock of To specify a language we need a stock of words as well as grammar to build words as well as grammar to build sentences. sentences.

CAN users specify their own CAN-based CAN users specify their own CAN-based language, or the user decides to use a language, or the user decides to use a standardized CAN-based higher-layer protocolstandardized CAN-based higher-layer protocol

Examples of CAN-based higher layer protocols Examples of CAN-based higher layer protocols

are are CANopenCANopen, , DeviceNetDeviceNet, , CANKingdomCANKingdom, , SDC, etc.SDC, etc.

DeviceNetDeviceNet

DeviceNet is an application layer protocol DeviceNet is an application layer protocol based on CAN 2.0A and is widely used in based on CAN 2.0A and is widely used in industrial automationindustrial automation

Originally developed by Rockwell / Allen- Originally developed by Rockwell / Allen- Bradley and is now an “open field” bus Bradley and is now an “open field” bus regulated by ODVA (Open DeviceNet regulated by ODVA (Open DeviceNet Vendors Association) Vendors Association)

It is an “open”, low level network that It is an “open”, low level network that provides connections between simple provides connections between simple industrial devices (such as sensors and industrial devices (such as sensors and actuators) to higher-level devices (such actuators) to higher-level devices (such as PLC controllers and computers)as PLC controllers and computers)

DeviceNet

DeviceNetDeviceNet

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

DeviceNetDeviceNet

This network allows a maximum of 64 logical This network allows a maximum of 64 logical nodes and supports 125, 250 and 500 nodes and supports 125, 250 and 500 Kbits/second data transfer ratesKbits/second data transfer rates

Each module is assigned some Each module is assigned some priorities/IDs, which are a function of the priorities/IDs, which are a function of the node number (called MAC ID) and should be node number (called MAC ID) and should be unique to avoid CAN specification violationunique to avoid CAN specification violation

Selectable end-to-end network distance Selectable end-to-end network distance varies with speedvaries with speed 125 Kbps 500 m (1,640 ft) 125 Kbps 500 m (1,640 ft) 250 Kbps 250 m (820 ft) 250 Kbps 250 m (820 ft) 500 Kbps 100 m (328 ft) 500 Kbps 100 m (328 ft)

DeviceNetDeviceNet

Devices can be interfaced with Devices can be interfaced with network without removing powernetwork without removing power

Supports only Standard CANSupports only Standard CAN

Uses production/consumption model for Uses production/consumption model for module to module transfer module to module transfer

Peer-to-Peer with Multi-Cast (one-to-Peer-to-Peer with Multi-Cast (one-to-many); Multi-Master and Master/Slave many); Multi-Master and Master/Slave Polled or change-of-state Polled or change-of-state

Components of DeviceNet DeviceComponents of DeviceNet Device

DeviceNetDeviceNet

Each of these components are organized Each of these components are organized into attributes, services (methods or into attributes, services (methods or procedures), and behaviors of the procedures), and behaviors of the componentscomponents

These objects are defined by DeviceNet These objects are defined by DeviceNet specification. For instance, the identity specification. For instance, the identity object has attributes such as vendor ID, object has attributes such as vendor ID, device type, and serial number.device type, and serial number.

DeviceNetDeviceNet

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 I/O data format (including definition of

assembly object(s) for efficient data assembly object(s) for efficient data transfer and,transfer and,

the device’s configurable parameters the device’s configurable parameters documented in electronic data sheet documented in electronic data sheet

(EDS(EDS) )

Smart Distributed Systems (SDS)Smart Distributed Systems (SDS)

Developed by Honeywell's MICRO Developed by Honeywell's MICRO SWITCH DivisionSWITCH Division

is also an advanced CAN based device-is also an advanced CAN based device-level communication network bus system level communication network bus system for intelligent sensors and actuators for intelligent sensors and actuators

The SDS Application Layer Protocol is The SDS Application Layer Protocol is optimized for “Smart Sensors and optimized for “Smart Sensors and Actuators”, where Configuration, Actuators”, where Configuration, Diagnostic, and Process information can be Diagnostic, and Process information can be embedded cost-effectively in a very small embedded cost-effectively in a very small footprintfootprint

Features of SDSFeatures of SDS

Communication bit transfer rates are 125, Communication bit transfer rates are 125, 250, 500, and 1,000 kBaud250, 500, and 1,000 kBaud

1500 ft maximum distance at 125 kBaud 1500 ft maximum distance at 125 kBaud (longer with Bridge)(longer with Bridge)

Maximum of 125 modules can be Maximum of 125 modules can be connected to the networkconnected to the network

12-24VDC, 2 power wires + 2 12-24VDC, 2 power wires + 2 communication wires + shieldcommunication wires + shield

126 logical addresses - not related to 126 logical addresses - not related to physical location on the networkphysical location on the network

Event-Driven, Master-Slave, Multicast and Event-Driven, Master-Slave, Multicast and Peer to Peer Services Peer to Peer Services

ExampleExample

Use of SDS interface with state of art sensorsUse of SDS interface with state of art sensors

Temp.

A/D

SDS

Substrate

RJ45

Press.

A/D

SDS

Substrate

RJ45

Substrate

SDSSDS

Small and effective way to connect small Small and effective way to connect small devices to a master controller. devices to a master controller.

Master has 100% control of all modules. Master has 100% control of all modules. No support for communication between No support for communication between

modules without a master PLC. modules without a master PLC. Supports only Standard CAN.Supports only Standard CAN. Effective when it comes to connect I/O Effective when it comes to connect I/O

devices (e.g., on/off switches, proximity devices (e.g., on/off switches, proximity sensors, etc.) to a PLC, as SDS sensors, etc.) to a PLC, as SDS fundamentally is a point to point fundamentally is a point to point communication between a master (Host) communication between a master (Host)

and remote I/O’sand remote I/O’s. .

SDSSDS

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

ComparisonComparison

SDS SDS DeviceNetDeviceNet

Possible bit ratesPossible bit rates 125k, 250k, 125k, 250k, 500k, 1M 500k, 1M

125k, 250k, 500k 125k, 250k, 500k

Protection Protection against modules against modules with incorrect bit with incorrect bit rate rate

Yes. Yes. NoNo

Possible node Possible node numbers. numbers.

0-125 0-125 0-63 0-63

Default node Default node numbernumber

125125 6363

Questions??Questions??