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Reference Manual

00809-0100-4811, Rev DA

Appendix C: Rosemount 3300 Series with HART

to Modbus

Converter

January 2015

Rosemount 3300 Series with HART

to Modbus

Converter

Table C-7. Implemented Functions of Levelmaster Protocol

Table C-8. Letters and Expressions Used in Previous Tables

C.8.5 Modbus ASCII communication setup

The parameter, default, and configurable values are shown in Ta bl e C -9 below.

Table C-9. Modbus ASCII Communication Parameters

Input format Description Output format

UnnN? Return ID number UnnNnnCcccc

UnnNmm Set ID number UnnNOKCcccc

UnnF? Return number of floats UnnFxCcccc

UnnFx? Set number of floats UnnFOKCcccc

Unn? Return floats and other data UnnDddd.ddFfffEeeeeWwwwCcccc

(1)

(1) In this case, number of floats is set to 1. If number of floats is set to 2, the Output Format would be:

UnnDddd.ddDddd.ddFfffEeeeeWwwwCcccc

Note

If one float is sent, it is “Float1”. If two floats are sent, it is “Float 1” before “Float 0”.

Letter Description

nn is used to identify slave to respond,

nn is a number 00-99 or ** (wildcard).

The EmulCtrl Address Holding register can be configured to a higher value than 99. In that

case, the address will be truncated to 99.

mm mm is the new ID number for the slave; mm is a number 00-99.

x x is the number of floats returned when slave receives Unn?, x is a number 0-2.

cccc Is the 16 bit CRC checksum, cccc are hexadecimal characters.

ddd.dd ddd.dd is the distance value from slave 1. Note that the first d can also be a ‘-’ (minus).

Float 1 Slave 1 PV.

Float 0 Slave 1 SV.

fff The temperature value. Configured by Holding Register 3208 in HMC.

(1)

(1) Any of the four available variables from any of the five HART slaves can be selected as the temperature source.

The least four significant bits (bit 0-3) select the variable number. Bits 4-7 select the HART slave address. If invalid values are

used, the temperature value will be invalid, with no Error bit set.

For example, if we want to use FV from HART Slave 3 as temperature source, we have to write the value 34 Hex (52 decimal).

eeee

An error value.

Bit 0: Invalid SV value (Float 0).

Bit 8: Invalid Temperature value.

Bit 12: Invalid PV value (Float 1).

Wwww A warning value, not used in this implementation.

Parameter Default value Configurable values

Baud Rate 9600 1200, 2400, 4800, 9600, 19200

Start Bits One One

Data Bits Seven Seven, Eight

Parity None None, Odd, even

Stop Bits One One or Two

Address 1 1-255

1 2 ... 196 197 198 199 200 201 202 203 204 205 206 ... 223 224

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