ATI Technologies d12 series - HART Transmitter, Point-To-Point (2-Wire); Figure 15. HART Operation, Point-To-Point (2-Wire)

ATI Series D12 Toxic Gas Transmitter with H10 Smart Sensor
Revision N (7/15) 20
HART Transmitter, Point-to-Point (2-Wire)
The HART “Point-to-Point” connection permits the transmitter to communicate digitally, while
retaining the functionality of its 4-20mA current loop. Setting the transmitter’s polling address to 0
permits the current loop to function normally. According to HART specifications, the current loop
must be terminated with a load resistor between 230 and 1100 ohms; however, transmitter
specifications restrict the maximum analog output resistance to a lower value (see Specifications). The
term, “active source”, refers to a transmitter that is not loop powered, and sources current from power
applied to it on separate terminals. Size the power supply according to the number of transmitters, the
current demand of each transmitter (see specifications), and wire resistance. Wire resistance must not
be allowed to drop the Primary Supply Voltage below 12V at the terminals of any transmitter. Hint:
use at least 14 AWG wire on supply connections (shown in bold).
Figure 15. HART Transmitter Operation, Point-to-Point (2-Wire)
-
Loop Supply Voltage
(12v Minimum)
+
Current Loop Receiver/Alarm
Module with Integral 24V Supply
For Digital and Analog Signaling
TB1
Bell202
Modem
Optional
Barrier/Isolator
for Hazardous
Locations
DCS or SCADA System
(primary master)
Hand-hel
d Communicator
(secondary master)
-
+
0.0
-
+
Gnd
Sig
Load Resistor for
Digital Signaling Only
OR
24
Channels are typically not
isolated from the supply, and
must include appropriately
sized load resistor between
230 ohms, and the maximum
analog output resistance stated
in the transmitter specifications.
Primary Supply
12 to 30 VDC
Class 2 Power
Source
-
+
24