C-3
Model 268 SMART FAMILY Interface
CONNECTIONS AND
HARDWARE
The Model 268 can communicate with a transmitter from the control
room, the transmitter site, or any other wiring termination point in the
loop. To communicate, it must be connected in parallel with the
transmitter; the connections are non-polarized.
Figure C-2. Connecting the Model 268
to a Transmitter Loop.
BASIC FEATURES
The basic features of the Model 268 include the Alphanumeric Keys,
Dedicated Keys, and Function Keys. The dedicated key functions are
always the same; the functions of the function keys vary depending on
the task being performed.
Dedicated Keys
On/Off
Use this key to turn the unit on and off. When you first turn on the
Model 268 it searches for a smart transmitter in the 4–20 mA loop. If it
does not find a smart transmitter, the Model 268 offers the opportunity
to try again. To do so, select “MULT DROP” or “OFF-LINE.”
Process Variable
Use the Process Variable key to display up-to-date process variable
readings from the transmitter in engineering units, milliamps, pulse
rate, and shedding rate. It also displays totalized flow.
Review
The Review key allows you to step through all the information
currently held in the four memory locations of the transmitter and
Model 268—SAFE MEM, OFLN MEM, WORK REG, and XMTR MEM.
See “Safety Messages” on page C-1 for complete warning information.
Power
Supply
250
V
≤
R
L
≤
1100
V
Power/Signal Terminals
Signal loop may be grounded at
any point or left ungrounded.
A HART-based communicator
may be connected at any
termination point in the signal
loop. Signal loop must have
between 250 and 1100 ohms
load for communications.
3
144-
0000
A
04A
