Advisor A90 Modbus Interface Guide Issue : 1 8th November 2017 1
This guide applies to the following models: A90-xx-M - Panel mounted, Safe Area A90-SS-xx-M - Rugged Panel mounted, Safe Area Note : The optional RS485 Communications module (-M) must be fitted 2
Contents Table of Contents Introduction........................................................................................................................................................................4 What’s in this Modbus Interface Guide........................................................................................................................4 What’s in the Instruction Manuals...............................................................................................................
Introduction This guide gives all the necessary information to use our Advisor A90 process meter in a Modbus installation. For hardware installation information, please refer to the separate instruction manuals available for each model.
Product Overview A detailed overview of the instrument is given in the instruction manual for each product. This should be read before implementing any system using these instruments, however a summary of the main features is listed below: Function The Advisor A90 Universal Panel Meter is a multicolour five digit display instrument, primarily intended for displaying a current, voltage or resistance analogue process signal in engineering units.
Modbus Implementation The Modbus implementation on the Advisor has several objectives. It offers the following services to the Modbus Master (PLC, PC or similar): • • • Monitor the process variable measured by the instrument Identify the status of the instrument (Alarms status, Tare Activation status,…) Configure the instrument remotely The Modbus interface is available as an optional module on the Advisor A90. The supported protocol is Modbus RTU (Modbus over RS485).
Supported Modbus Functions The Modbus functions that are supported by the A90 are as follows: Decimal Hex Description 01 0x01 Read Coils 02 0x02 Read Discrete Inputs 03 0x03 Read Holding Registers 04 0x04 Read Input Registers 05 0x05 Write Single Coil 06 0x06 Write Single Register 08 0x08 Diagnostics (Partly Supported) 15 0x0F Write Multiple Coils 16 0x10 Write Multiple Registers 43 0x2B Read Device Identification (Partly Supported) Diagnostics (Function Code 0x08) All of th
Read Device Identification (Function Code 0x2B) Only the MEI type 14 is supported in this function, and all other types are rejected. This function code allows reading the identification and additional information from a remote device. There are 3 categories of objects defined in the following table. The table also specifies the value and message length from the instrument for each object ID.
Modbus Register Address Map Notes: In the tables below (IEEE) indicates that data is represented by a 4 byte IEEE floating point format For 32 bits registers (integers or floats), the Most Significant 16 bits word is the one with the highest Modbus address.
Holding Read / Registers Write Address Registers Description Default Range 1 3 5 7 9 11 13 15 17 19 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 42 43 44 45 46 47 48 49 50 51 52 54 55 201 203 204 206 207 209 210 212 213 215 216 218 219 221 222 224 225 227 228 230 2 2 2 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 1 1 1 1 1 1 1 1 1 1 2 1 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 8 1 0.0 100.0 * * 0.0 0.0 0.0 0.
Notes: Input Unit Enumeration: (Only for Temperature Inputs) 0 = Degrees Celsius 2 = Degrees Fahrenheit 4 = Resistance 1 = Degrees Kelvin 3 = Degrees Rankine Function (Root extraction) (Only for Current Inputs) 0 = No Root extraction 1 = Root extraction Resolution (of least significant digit) 0=1 2=5 1=2 3 = 10 D.P. (Decimal Point position on the Display:) 0 = 00000 (No Decimal Point) 2 = 000.00 4 = 0.0000 1 = 0000.0 3 = 00.
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