Temperatureis generally sensed at the tip of the probe. To get an accurate tem-
perature measurement theprobe sheath should be well immersed, with ade-
quate depth and fit, into the medium to be measured.
CAUTION: Probes are fragile devices that can be easily damaged by me-
chanical shock, overheating, and absorption of moisture or fluids in the
wires or hub. Damage may not be visibly apparent but nevertheless can
cause drift, instability, and loss of accuracy. Observe the following pre-
cautions:
Do not allowprobes to be dropped, struck, bent, or stressed.
Do not overheatprobes beyond their recommended temperature range.
Do not allowany part of the probe other than the sheath to be immersed in
fluid.
Do not allowthe probe hub or wires to be exposed to excessive temperatures.
Keepthe probe wires clean and away from fluids.
6.6 INFO-CON Connector
The probe connects to thetop of the1521 using a Hart INFO-CON connector
(see Figure3 on page 17). The probe connector will fit snugly and lock into
place when it is fully inserted. The connector includes a memory device that
stores theunique characteristics of the probe, allowing the instrument to mea-
sure temperature accurately.Generally, the probe will be purchased with the
connector attached and programmed by the factory.Connectors can be pur-
chased separatelyand installed onto probes by the user. The INFO-CON can be
programmed directlyfrom the 1521 by authorized personnel.
If it is necessary to install the INFO-CON onto a probe in the field followthe
diagram belowfor connecting the wires of the probe to the connector terminals.
Beforeopening the INFO-CON case, be sure to be grounded with an ESD strap
to avoiddamaging the memory chip. For four-wire probes, one pair of wires at-
taches to terminals C1 and P1 and theother pair attaches to terminals C2 and
P2. (C1 and C2source current and P1 and P2 sense the potential.) If a shield
wire ispresent it should be connected to the GND terminal (see Figure 6).
A three-wireor two-wireprobe can also be used with the 1521. A three-wire
probe is connected by attaching the common wires to the C1 and P1 terminals
and the other wireto the C2 and P2 terminals.The two-wire probe is connected
by one wire to the C1 and P1 terminals and the other wire to C2 and P2. Again,
anyshield wire should be connected to the GND terminal (see Figure 6). Rec-
23
6 General Operation
INFO-CON Connector