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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 allows reading and writing data into Fisher-Rosemount RS3 system by means of RNI Ethernet network driver (Remote Network Interface) -there is used TCP/IP network communication.

Communication uses the following methods for data acquisition from RNI:

  • DDS: Dynamic Data Server – acquisition of process tag values when they change.
  • RW Services: Read/Write Services – used for value writing 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,
  • 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 to find RNI IP address (in the OS Win NT, 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 file userfile.cfg – 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 there is required writing to RS3, the user access rights must be CONFIGURE.

I/O tag configuration

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

Address is the name of of 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 - tag output (Q) =1H-01

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

=7A-02.@ - all @ tag flags =7A-02 as 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. RS3 tag name is each valid tag name.
  2. RS3 address is in form of =NXXNNN for I/O blocks and =NX-NN 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 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 of T, the tag name is followed by the character (.) and a ‘command‘.

Item name D2000 type I/O Comment
T or T.Q AI, AO I/O Output Value
T.VS CI I System Flags – all
T.MD CI, CO I/O Block Mode
T.A up to T.O AI, AO I/O Input Values
T.U CI, CO I/O User 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, DO I/O User Flag – individually
T.@ CI I/O Discrete Inputs – all
T.@a up to T.@p DI I/O Discrete Input – individually
T.TS CI I T System Flags
T.UMD CI I User Modes
T.SA up to T.SO CI I System Flags A – O
T.UA up to T.UO CI I User Flags A – O
T.ATP AI I Auto Tune Phase
T.AGF AI I Actual Gain Factor
T.CGF AI I Calculated Gain Factor
T.AIT AI I Actual Integral Time
T.CIT AI I Calculated Integral Time
T.ADT AI I Actual Derivate Time
T.CDT AI I Calculated Derivate Time

When you configure an I/O tag, you must select one of four radio buttons (UR1 to UR4) of the parameter Update rate. The update rate is used by the DDS service and defines a data read period from RS3. The update rate is configured on the boot computer in the file dds.cfg.



Changes and modifications


Document revisions

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