Siemens ESM, OSM Deleting Addresses, Setting the Transmission Rate, Autonegotiation

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Functions

Deleting Addresses

An OSM/ESM monitors the age of the addresses it has learnt - address entries that exceed a certain age (aging time, default setting on the OSM/ESM 40 seconds) are deleted again by the OSM/ESM. If a packet with a source address matching the address entry is received before the aging time elapses, the address entry is retained and the age of the address is set to 0 again. When the OSM/ESM is restarted, the address entries are also deleted. If a packet is received by an OSM/ESM for which there is no address entry, the OSM/ESM distributes it to all ports.

Setting the Transmission Rate, Autonegotiation

The electrical ports of the OSM/ESM are set to autonegotiation mode as default (autosensing).

They automatically detect the transmission rate (10 or 100 Mbps) at which the attached device or attached network segment operates and set themselves to this rate. If the partner device also supports the autonegotiation mode, the devices further negotiate whether they will exchange data with each other in the half duplex or full duplex mode.

As a result of the automatic adaptation to the transmission rate of the attached DTEs, existing network segments operating at 10 or 100 Mbps can be interconnected simply using OSMs/ESMs.

Note

If the partner device connected to a port of an OSM/ESM does not support the autonegotiation mode (for example OSM Version 1), the port of the partner device must be set to half duplex mode or the port properties of the OSM/ESM must be configured.

Packets with the VLAN Priority Tag

OSMs/ESMs support frames with VLAN tags according to IEEE 802.1Q.

VLAN tags are additional information entered in the frame header. This additional information includes a priority field according to IEEE 802.1D. This field can have values from 0 through 7 and allows frames to be assigned a priority from 0 (lowest priority) through 7 (highest priority).

Frames with priority 0 through 3 are processed with low priority in the OSMs/ESMs and frames with priority 4 through 7 are processed with high priority.

Frames with a non-learned unicast destination address are an exception. These are always handled with low priority.

26	Industrial Ethernet OSM/ESM
	C79000-Z8976-C068-10

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Contents Simatic NET Classification of Safety-Related Notices Copyright Siemens AG 2000/02, All rights reservedQualified Personnel Safety Instructions Regarding your ProductTrademarks Correct Usage of Hardware ProductsCorrect Usage of Software Products Prior to StartupPurpose of the Operating Instructions Installing an OSM/ESMPreface PackageValidity of the Operating Instructions Further DocumentationFinding Information Personnel Qualification Requirements Guide to the ManualAudience Standards and ApprovalsContents Introduction Introduction Overview of the Variants of the OSM/ESM OSM ITP62Possible Attachments Properties of the OSM ITP62 OSM ITP62-LD OSM ITP62-LDProperties of the OSM ITP62-LD ITP62-LDOSM ITP53 OSM ITP53Properties of the OSM ITP53 ESM ITP80 ESM ITP80Properties of the ESM ITP80 OSM TP62 OSM TP62Properties of the OSM TP62 ESM TP80 ESM TP80Properties of the ESM TP80 OSM BC08 OSM BC08Properties of the OSM BC08 OSM TP22 OSM TP22Properties of the OSM TP22 ESM TP40 ESM TP40Properties of the ESM TP40 Functions Simple Network Configuration and Network ExpansionLimitation of Errors to the Network Segment Affected Increased Network PerformanceSetting the Transmission Rate, Autonegotiation Deleting AddressesPackets with the Vlan Priority Tag Functions Network Topologies with OSM/ESM Bus Structure Bus with OSMBus with ESMs Redundant Ring Structure Redundant Ring Structure with OSMsESM in RM mode Redundant Coupling of Network Segments OSM/ESM Port Assignment in the Standby Mode Simultaneous Standby and Redundancy Manager OperationReplacing the Standby Master During Operation OSM RM mode Compatibility of OSM Version 2/ESM with OSM/ORM Version CompatibilityRing with OSM Version 2 as Redundancy Manager Redundant Coupling of Rings Standby Master Slave OSM Coupling Network Segments RM mode OSMInterfaces, Displays and Operator Controls ITP/TP Ports ITP PortsTP Ports Link Control Autonegotiation ModeProperties of the TP/ITP Ports Auto Polarity ExchangeInterfaces, Displays and Operator Controls FO Ports Standby-Sync Port Serial Interface PinoutTerminal Block for the Power Supply and Signaling Contact Power Supply Signaling ContactRM Mode additional OSM/ESM in the Standby Mode Digital Inputs Input voltage must not exceed +30V DC or fall below -30V DCLED Display Status Fault red LEDDisplays and Operator Controls Stby Standby green LEDRM Redundancy Manager green LED LED Power Display mode MeaningFault Mask Port LEDs DisplayFull duplex Port LED Two-Pin DIP Switch DIP SwitchesSelect/Set Button Installation, Commissioning, Cleaning Maintenance Do not install damaged components Unpacking, Checking the ConsignmentInstallation PreparationsInstalling the OSM on a DIN Standard Rail Standard Rail MountingRemoving from a Standard Rail Removing from the Standard RailInstallation on a Simatic S7-300 Rail Installation on the S7-300 RailInstallation in Pairs in the 19 Cubicle Installation in the 19 CubicleWall Mounting Wall MountingWall Mounting Cleaning Maintenance Firmware Update Specifying the keyword OSM FirmwareFirmware Update Firmware Update Firmware Update Firmware Update Technical Specifications PortsTechnical Specifications Switching Properties of OSM/ESM Permitted Cable LengthsCascading Depth Mechanical Design Only horizontal installationPermitted Ambient Conditions/EMC PermittedConsignment / Order Numbers Accessories Standards and Approvals Product nameCE Mark UL Approval Area of ApplicationApproval for Australia CSA CertificationFM Approval Adherence to Installation Instructions Fault Mask Filtering ITP Port GlossaryLatency Link ControlTP Port Industrial Ethernet OSM/ESM C79000-Z8976-C068-10 References Http//www4.ad.siemens.de/view/cs/de/8677203Industrial Ethernet OSM/ESM C79000-Z8976-C068-10 Index Ambient conditions, permittedIndex