Instruction manual

7
MODEL XMT-C SECTION 1.0
DESCRIPTION AND SPECIFICATIONS
1.7 FOUNDATION FIELDBUS
Figure 1-3 shows a Xmt-C-FF being used to measure conductivity. The figure also shows three ways in which Fieldbus
communication can be used to read process variables and configure the transmitter.
FIGURE 1-3. CONFIGURING MODEL XMT-C TRANSMITTER WITH FOUNDATION FIELDBUS
1.6 HART COMMUNICATIONS
1.6.1 OVERVIEW OF HART COMMUNICATION
HART (highway addressable remote transducer) is a digital communication system in which two frequencies are superim-
posed on the 4 to 20 mA output signal from the transmitter. A 1200 Hz sine wave represents the digit 1, and a 2400 Hz
sine wave represents the digit 0. Because the average value of a sine wave is zero, the digital signal adds no dc compo-
nent to the analog signal. HART permits digital communication while retaining the analog signal for process control.
The HART protocol, originally developed by Fisher-Rosemount, is now overseen by the independent HART
Communication Foundation. The Foundation ensures that all HART devices can communicate with one another. For more
information about HART communications, call the HART Communication Foundation at [phone]. The internet
address is http://www.hartcomm.org.
1.6.2 HART INTERFACE DEVICES
The Model 375 HART Communicator is a hand-held device that provides a common link to all HART SMART instru-
ments and allows access to AMS (Asset Management Solutions). Use the HART communicator to set up and control the
XMT-C-HT and to read measured variables. Press ON to display the on-line menu. All setup menus are available
through this menu.
HART communicators allow the user to view measurement data (conductivity, TDS, resistivity, and temperature), program
the transmitter, and download information from the transmitter for transfer to a computer for analysis. Downloaded informa-
tion can also be sent to another HART transmitter. Either a hand-held communicator, such as the Rosemount Model 375, or
a computer can be used. HART interface devices operate from any wiring termination point in the 4 - 20 mA loop. A mini-
mum load of 250 ohms must be present between the transmitter and the power supply. See Figure 1-4.
If your communicator does not recognize the Model XMT-C transmitter, the device description library may need updating.
Call the manufacturer of your HART communication device for updates.
XMT-C-FF
conductivity
HCl