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OPC-Server Data Sheet Login
Created by Werner Krings, Tani GmbH
Creation date: 2019.7.1, last modified 2022.2.15

Technical Data Opc Server


The Tani OPC Server is a multi protocol and multi OPC server. It allows access to controllers and devices from various manufacturers. It is easily to configure. It offers a lot of diagnostics functions.

OPC Interfaces

The maximum number of OPC clients is depending on used resources only. A PC from 2014 can handle multiple hundred connections.
All OPC interfaces are working locally in one PC or over network.
in case of Classic OPC Classic please do not use DCOM over networks, but it will be supported.
OPC UA supports the fast binary protocol. Security is supported in all variants. Multicast discovery is supported.
Data access data items are supported up to 200K each.

OPC UA functionality and limitations

The OPC UA implementation conforms to the specification 1.05.
The OPC UA Standard Model is supported, some extensions exist.
The maximum single request and answerlen is 16m
The OPC UA Alarms & Conditions module is supported. This includes filters, history.
An internal discovery server is active on standard, it supports multicast discovery also. It can be used as a global discovery server. Alternatively an external discovery server can be configured.
The certificate management GDS Push is supported.

The session timeout will be limited to one hour.
The server and client certificate will be renewed if the Tani self signed certificate is used. All other certificates remain unaffected on expiring. The certificate validity is checked all 12h. It will be renewed seven days before it expires. Running connections will not be affected, new connections will use the new certificate.
AddNodes is supported with the following restrictions:

Machine models from the OPC Foundation or the VDMA directly can be loaded with its corresponding XML file.

The security certificate key minimum length are

Traffic between different OPC interfaces (tunneling) is supported. It will be used for the OPC DA tunnels.

Controller Interfaces

All controllers will be connected over network. Often this is Ethernet, WLAN or other networks. All serial Ethernet and MPI Ethernet gateways for industrial controllers usage are supported.

Configuration Interfaces

The configuration can be done with the shipped configuration software or over OPC with the System topic.
The connection  for the configuration is encrypted with TLS 1.2. The encryption can be switched off for usage in countries where encryption is forbidden.

Network Redundancy for connections to controllers and devices

Connections to devices and controllers are supporting network redundancy.
Double and triple redundancy can be selected.
Two redundancy operation modi are possible.
In dynamic redundancy any of the connections is working as master. If it breaks another connection becomes the master connection.
In static redundancy the first connection is the master. If it breaks another connection becomes the master. If the first connection works again it will become the master connection again.

The connections of the redundancy should work on different network adapters.The adapters need different IP subnets for properly work.

Controller Types and Controller Protocols

Communicates via Ethernet.


BACnet will be used over IP / UDP.
Maximum length of strings: 256 Byte
Status text elements are supported (state_text)
Supported charsets: UTF-8, UTF-16, Latin-1
Unions ("Choice") and structures ("Sequence") are existing for important values as trend, shedule, calendar, prioriry.
The trend data are offered as history data. All unimplemented instances will not be shown.
Enum values are represented as UINT32. Some special enum are handled as bool.
Values in "Octet-String" and "Bit-String" can be written in whole only.

BBMD (BACnet Broadcast Management Device) details

BBMD will be used during the connection establishing and the device search if the devices do not be all in the same collision domain. BACnet uses broadcast during ist connection establishing.
There are several procedures in BBMD:

Additionally BBMD can be used connecting older serial only installations to the IP network.

COV (Change Of Values) details

COV represents the event subsystem of BACnet. Events will be offered in browsing the variables, they will be subscribed. If the device will send the data the event will be generated.
Because BACnet is working with UDP the COV receive can not be guaranteed. Tani is offering an option: If no event will be received during the reconnection time from the configured connection it will be polled. If the value did not change no event is send for this polling.

BACnet - Writing values with priority-array

These object types have a priority-array in addition to their present-value property: The BACnet spec says: The Tani implementation works as follows:

This mechanism was chosen to allow choosing the write priority via OPC without changing the read syntax for present-value property. This also allows writing NULL values via OPC.

Implemented Properties

The following object properties are implemented:

Object TypePropertyBACnet TypeOPC TypeRemarks
allallBit StringArray of Boolean
allallCharacter StringString
allallOctet StringArray of UInt8
allChange of State Time (16)BACnetDateTimeDateTime
allEvent Time Stamps (130)Sequence of BACnetTimeStampArray of Structure "Timestamp"
allObject Type (79)BACnetObjectTypeUInt32
allTime of Active Time Reset (114)BACnetDateTimeDateTime
allTime of State Count Reset (115)BACnetDateTimeDateTime
Access Door (30)Door Alarm State (226)BACnetDoorAlarmStateUInt32
Access Door (30)Present Value (85)BACnetDoorValueUInt32
Access Door (30)Priority Array (87)BACnetPriorityArrayArray(1..16) of Structure "UnsignedPriorityValue"see section "Priority Array"
Access Door (30)Status Flags (111)BACnetStatusFlagsArray(0..3) of Boolean
Analog Input (0)Present Value (85)RealFloat
Analog Input (0)Status Flags (111)BACnetStatusFlagsArray(0..3) of Boolean
Analog Output (1)Present Value (85)RealFloat
Analog Output (1)Priority Array (87)BACnetPriorityArrayArray(1..16) of Structure "AnalogPriorityValue"see section "Priority Array"
Analog Output (1)Status Flags (111)BACnetStatusFlagsArray(0..3) of Boolean
Analog Value (2)Present Value (85)RealFloat
Analog Value (2)Priority Array (87)BACnetPriorityArrayArray(1..16) of Structure "AnalogPriorityValue"see section "Priority Array"
Analog Value (2)Status Flags (111)BACnetStatusFlagsArray(0..3) of Boolean
Averaging (18)Maximum Value Timestamp (149)BACnetDateTimeDateTime
Averaging (18)Minimum Value Timestamp (150)BACnetDateTimeDateTime
Binary Input (3)Present Value (85)BACnetBinaryPVUInt32
Binary Input (3)Status Flags (111)BACnetStatusFlagsArray(0..3) of Boolean
Binary Output (4)Present Value (85)BACnetBinaryPVUInt32
Binary Output (4)Priority Array (87)BACnetPriorityArrayArray(1..16) of Structure "UnsignedPriorityValue"see section "Priority Array"
Binary Output (4)Status Flags (111)BACnetStatusFlagsArray(0..3) of Boolean
Binary Value (5)Present Value (85)BACnetBinaryPVUInt32
Binary Value (5)Priority Array (87)BACnetPriorityArrayArray(1..16) of Structure "UnsignedPriorityValue"see section "Priority Array"
Binary Value (5)Status Flags (111)BACnetStatusFlagsArray(0..3) of Boolean
Calendar (6)Datelist (23)List of BACnetCalendarEntryArray() of Structure "BACnet.CalendarEntry"
Device (8)Last Restore Time (87)BACnetTimeStampStructure "Timestamp"
Device (8)Local Date (56)DateStructure "Date"
Device (8)Local Time (57)TimeStructure "Time"
Device (8)Object List (76)Sequence of BACnetObjectIdentifierArray of UInt32
Device (8)Protocol Object Types Supported (96)BACnetObjectTypesSupportedArray of Boolean
Device (8)Protocol Services Supported (97)BACnetServicesSupportedArray of Boolean
Device (8)Segmentation Supported (107)BACnetSegmentationUInt32
Device (8)System Status (112)BACnetDeviceStatusUInt32
Device (8)Time of Device Restart (203)BACnetTimeStampStructure "Timestamp"
Event Enrollment (9)Object Property Reference (78)BACnetDeviceObjectPropertyReferenceStructure "DeviceObjectPropertyReference"
File (10)Modification Date (149)BACnetDateTimeDateTime
Life Safety Point (21)Present Value (85)BACnetLifeSafetyStateUInt32
Life Safety Point (21)Status Flags (111)BACnetStatusFlagsArray(0..3) of Boolean
Life Safety Zone (22)Present Value (85)BACnetLifeSafetyStateUInt32
Life Safety Zone (22)Status Flags (111)BACnetStatusFlagsArray(0..3) of Boolean
Load Control (28)Actual Shed Level (212)BACnetShedLevelStructure "ShedLevel"
Load Control (28)Duty Window (213)UnsignedUInt32
Load Control (28)Expected Shed Level (214)BACnetShedLevelStructure "ShedLevel"
Load Control (28)Present Value (85)BACnetShedStateUInt32
Load Control (28)Requested Shed Level (218)BACnetShedLevelStructure "ShedLevel"
Load Control (28)Shed Duration (219)UnsignedUInt32
Load Control (28)Start Time (142)BACnetDateTimeDateTime
Loop (12)Controlled Variable Reference (19)BACnetDeviceObjectPropertyReferenceStructure "DeviceObjectPropertyReference"
Loop (12)Manipulated Variable Reference (60)BACnetDeviceObjectPropertyReferenceStructure "DeviceObjectPropertyReference"
Loop (12)Setpoint Reference (109)BACnetSetpointReferenceStructure "SetpointReference"
Loop (12)Present Value (85)RealFloat
Loop (12)Status Flags (111)BACnetStatusFlagsArray(0..3) of Boolean
Multi State Input (13)Alarm Values (7)Sequence of UnsignedArray of UInt32
Multi State Input (13)Fault Values (39)Sequence of UnsignedArray of UInt32
Multi State Input (13)Present Value (85)UnsignedUInt32
Multi State Input (13)Status Flags (111)BACnetStatusFlagsArray(0..3) of Boolean
Multi State Output (14)Present Value (85)UnsignedUInt32
Multi State Output (14)Priority Array (87)BACnetPriorityArrayArray(1..16) of Structure "UnsignedPriorityValue"see section "Priority Array"
Multi State Output (14)Status Flags (111)BACnetStatusFlagsArray(0..3) of Boolean
Multi State Value (19)Alarm Values (7)Sequence of UnsignedArray of UInt32
Multi State Value (19)Fault Values (39)Sequence of UnsignedArray of UInt32
Multi State Value (19)Present Value (85)UnsignedUInt32
Multi State Value (19)Priority Array (87)BACnetPriorityArrayArray(1..16) of Structure "UnsignedPriorityValue"see section "Priority Array"
Multi State Value (19)Status Flags (111)BACnetStatusFlagsArray(0..3) of Boolean
Notification Class (15)Recipient List (102)List of BACnetDestinationArray() of Structure "BACnet.Destination"
Schedule (17)Effective Period (32)BACnetDateRangeStructure "DateRange"
Schedule (17)Exception Schedule (38)Sequence of BACnetSpecialEventArray of Structure "SpecialEvent"
Schedule (17)List of Object Property References (54)Sequence of BACnetDeviceObjectPropertyReferenceArray of Structure "DeviceObjectPropertyReference"
Schedule (17)Present Value (85)ABSTRACT-SYNTAX.&TypeStructure "Any"
Schedule (17)Schedule Default (174)ABSTRACT-SYNTAX.&TypeStructure "Any"
Schedule (17)Weekly Schedule (123)Sequence Size(7) Of BACnetDailySchedule7 sub-objects ("Monday", "Tuesday", ...) of Structure "TimeValue"
Pulse Converter (24)Present Value (85)RealFloat
Pulse Converter (24)Status Flags (111)BACnetStatusFlagsArray(0..3) of Boolean
Structured View (29)Subordinate List (211)Sequence of BACnetDeviceObjectReferenceArray of Structure "DeviceObjectReference"
Trend Log (20)Client COV Increment (127)BACnetClientCovStructure "ClientCov"
Trend Log (20)Log Buffer (131)BACnetLogRecordStructure "LogRecord"Accessed via "HistoryRead" function, "Read" shows only one record.
Trend Log (20)Log Device Object Property (132)BACnetDeviceObjectPropertyReferenceStructure "DeviceObjectPropertyReference"
Trend Log (20)Start Time (142)BACnetDateTimeDateTime
Trend Log (20)Stop Time (143)BACnetDateTimeDateTime


KNX will be used over IP / TCP and IP / UDP.
The symbol import is using the standarized ESF files.

Logger for diagnostics

The OPC Server contains a logger for diagnostics purposes during plant startup. The logger can be configured. The system load can be big if all controller data in big plants are logged.


Maximum number of configurable client connections: 4000.
Maximum length of a single item: 4GB.
Maximum number of elements each connection: 1 million.
Maximum number of elements (Items): 16 million.
Maximum OPC groups each connection: 100.
Maximum number of passive connection for each port is 999.
The OPC synchronous functions returning a bad quality immediately if the PLC connection is not established.
Changes in controller configuration will be checked all 10 seconds if the PLC does not offer a mechanism for this check during write.
Fields can be up to 64K in length each.
Multi dimensional arrays can have up to six dimensions.

Virtual Connections

Virtual connections provide a start point mostly used as destination for redirects.
A virtual connection has connection rights. The redirect destination in this connection will offer the rignts of the virtual connection. As in the logic tables and the status variable lists the source rights are ignored.
Symbols for the virtual connection can be defined in the symbol editor.
One PLC element can be used once in one virtual connection.

Simulation of PLC connections

Connections and their data can be simulated.
Read data creates the elements with value zero. Write will change the content. The changed values will be returned as new data.

Depending on the license the limits can be less.


The throughput will be mainly limited by the controller speed or the reaction time of OPC applications.
Read requests to the controller will be optimized as much the controller is supporting this. For that elements will be collected to blocks reading more than requested, but not for inputs and outputs. These optimizing can be affected by configuration separately for each connection. Optimizing can be switched off, too.
Write requests to the controller are collected or handled in that order the application did called the system.
On OPC all optimizing the individual OPC uses is supported.
The normal time in cyclic controller requests is 50ms.It can be faster if the controller polling interval is set to zero.
Only data are sent to OPC which did change in the controller between two read requests.

Field and text optimizings

The from version 1.8 existing field optimizings will prevent reading the long fields too often, the index is requested on standard only.This optimizing bases of the fact that the index does net changed too frequently.

Usage of memory

Usage of computation time

The consumed computation time is depending on the load with communication. Most the time it will be waited for controller data or OPC application reaction.
All software is working with events. This maximizes the throughput and minimizes the usage of computation time.
Multiple CPU are supported. Up to ten CPU will be used, the main work will be handled by three CPU.


The installation does depending on the product install multiple parts separately. On uninstall not all products are deleted automatically. But all installed products can be deleted over the menu or the software part in the system control manager.
The user settings will be preserved and not deleted during uninstall.

Automatic structure import

Type Auto-Import works for all client protocols that are able to use structures/enumerations and have online browsing functions. This includes:

These protocols have a fixed list of structures and don't need Auto-Import:

These protocols have online browsing, but don't use structures/enumerations:

All other protocols don't have online browsing.

Type Auto-Import is implemented in two steps:

  1. A structure or enumeration type which has not been imported is assigned a Node ID when:
    • the Item is being monitored (by calling CreateMonitoredItems):
    • the Item is being read/written (by calling Read/Write):
    • the Item is being registered (by calling RegisterNodes):
    • the DataType attribute of an Item with this type is accessed:
  2. A structure or enumeration type which has not been imported is actually imported when:
    • the Item is being monitored (by calling CreateMonitoredItems):
    • the Item is being read/written (by calling Read/Write):
    • the Item is being registered (by calling RegisterNodes):
    • the DataTypeDefinition attribute of the DataType node is read (after it has been created by step 1):
    • the EnumValues property node is read (for Enumerations, after it has been created by step 1):


Before Auto-Import Step 1, any types that have not been imported yet:

Before Auto-Import Step 2, any types that have not been imported yet:

After Auto-Import Step 2:

A client wishing to use a variable with a structure/enumeration type that has not been imported should

to trigger the type import. Only after completing one of these the structure type is available in the server.

Operating systems