Fisher-Rosemount RS3 RNI communication protocol

Supported device types and versions
Communication line configuration
Communication station configuration
I/O tag configuration
Changes and modifications
Document revisions

Supported device types and versions

The protocol implementation supports reading and writing data into the Fisher-Rosemount RS3 system by means of RNI Ethernet network driver (Remote Network Interface) -a TCP/IP network communication is used.

Communication uses the following methods for data acquisition from RNI:

  • DDS: Dynamic Data Server – acquisition of process tag values on-change.
  • RW Services: Read/Write Services – used for writing values into RS3.

The methods are described in the Fisher-Rosemount Systems RNI Programmer’s Manual documentation, Software Version 2.3, April 1997.

Communication line configuration

  • communication line category: API,
  • For the other parameters - see the D2000 System configuration.

Communication station configuration

  • Communication protocol: Fisher-Rosemount RNI.
  • Station address consists of the following parameters :
    • RNI Name – RNI name allows finding RNI IP address (in the Windows NT OS, the name together with the IP address is stored in the file %SystemRoot%\system32\drivers\etc\hosts)
    • Name – user access name (it is configured together with access rights on the boot PC for RNI in the userfile.cfg file – see the RNI configuration manual)
    • Password – password to given access menu

You must pay attention when you select the user's access right (D2000 KOM)  - if writing to RS3 is required, the user access rights must be CONFIGURE.

I/O tag configuration

Possible types: Ai, Ao, Ci, Co, Di, Do, TiA

The address is the name or address of the I/O RS3 tag. For analog I/O tags, the address can be defined in the following forms:


For example:

AI-701 - AI-701 tag output (Q)

=1H-01 - output (Q) of tag =1H-01

AI-701.B - B input of AI-701 tag

=7A-02.@ - all @ flags of tag =7A-02 as a 16-bit unsigned integer

For digital tags, the I/O address can be defined in the following forms:


Or if COMMAND is @:


For example:



  1. The RS3 tag name is each valid tag name.
  2. RS3 address is in =NXXNNN form for I/O blocks and in =NX-NN form for control blocks, where N is a number and X is a character.
  3. System flags and 'User' flags that are read as analog values are represented by a 16-bit unsigned integer.

The following table contains valid ‘command’ names for RNIDDE. The first column contains the short name of RS3 I/O tag as the letter T, the tag name is followed by the character (.) and a ‘command‘.

Item nameD2000 typeI/OComment
T or T.QAI, AOI/OOutput Value
T.VSCIISystem Flags – all
T.MDCI, COI/OBlock Mode
T.A up to T.OAI, AOI/OInput Values
T.UCI, COI/OUser Flags – all
T.U\a up to T.U\p or 

T.Ua up to T.Up or

T.a up to T.p

DI, DOI/OUser Flag – individually
T.@CII/ODiscrete Inputs – all
T.@a up to T.@pDII/ODiscrete Input – individually
T.TSCIIT System Flags
T.UMDCIIUser Modes
T.SA up to T.SOCIISystem Flags A – O
T.UA up to T.UOCIIUser Flags A – O
T.ATPAIIAuto Tune Phase
T.AGFAIIActual Gain Factor
T.CGFAIICalculated Gain Factor
T.AITAIIActual Integral Time
T.CITAIICalculated Integral Time
T.ADTAIIActual Derivate Time
T.CDTAIICalculated Derivate Time

When you configure an I/O tag, you must select one of four radio buttons (UR1 to UR4) to assign the I/O tag to one of the Update Rate groups. The Update Rate groups are used by the DDS service and they define a period of reading data from the RS3. The Update Rate groups are configured on the booting computer in the dds.cfg file.



Changes and modifications


Document revisions

  • Ver. 1.1 – February 9th, 2000 – Document update.
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