8
TWITE INSTRUMENTS
THERMOSTAT MODEL TD-196 OPERATING MANUAL
INSTALLATION CONT.
S
ENSOR
P
OSITIONING
.
The sensor
(and extra sensors, optional extra)
may be placed in any convenient
position keeping in mind that if more than one sensor was set to be used for control-
ling, the average of those sensors will the temperature used for control and will be
the temperature displayed in the normal
(not scan mode)
display mode while display-
ing the temperature.
The sensor or sensors used for control should be placed in the return air section for
cooling, and where applicable for heating.
The distance a sensor may be placed from the unit should not exceed
500 meters
The sensors must not be exposed to temperatures below -50.0 oC or above
+150.0 oC
Sensors and cables should not be fully immersed in any liquid for long periods of
time. They may be immersed for short periods for calibration purposes only. The
stainless steel sheath may be immersed in a liquid that will not corrode AISI 304
Stainless Steel.
P
RINTER
C
ONNECTION
(RS485).
Up to 16 units
(TD-196)
can be connected to a printer
(a standard EPSON ® or
compatible printer with a SERIAL interface)
for printing out of temperatures at
preset times, data logged temperatures and parameter set points.
All units in the chain must have their RS485 - terminals connected
together
(in parallel)
and their RS485 + terminals connected together
(in parallel)
using single twisted pair coaxial cable. The shield must be connected to GROUND at
one end only
(not at each unit).
To connect to a printer with an RS232 port, the TD-196's + serial
output must be connected to the rs232 receive input
(pin 3 on the 25 pin D connec-
tor)
and the ground output/input on the TD-196 connected to the signal ground of the
printer
(pin 7 on the 25 pin D connector).
The pins 4 & 5 on the 25 pin D connector
must be tied
(shorted)
together. This type of communication is only available if all
TD-196 units are in close proximity to each other and the printer,
(no more than 6
metres).
For longer distances and parrallel interface see later under Printer Communications
and Remote Display Module
