GENERAL DESCRIPTION
Model TC136 is a bi-directional control for independent thermoelectric modules or in conjunction
with auxiliary or supplemental resistive heaters for both cooling and heating applications. The “H”
bridge configuration of the solid state MOSFET output devices allows for the bi-directional flow of
current through the thermoelectric modules. Highly efficient N-channel output devices are used for
this control mode.
This controller is PC programmable via an RS232 communication port for direct interface with a
compatible PC. The RS232 communications interface has 1500 VAC isolation from all other
electronic circuitry minimizing interference from noise or errant signals caused by common ground
loops. The easily accessible communications link permits a variety of operational mode configu-
rations. Field selectable parameters or data acquisition in a half duplex mode can be performed.
This controller will accept a communications cable length in accordance with RS232 interface
specifications.
Once the desired set parameters are established, the PC may be disconnected and Model TC-136
becomes a unique, stand-alone controller. All parameter settings are retained in non-volatile memory.
The user friendly, communications software requires no prior programming experience to estab-
lish operation. A command set is provided for qualified personnel to program a software inter-
face or use as an embedded control.
Mechanically, the control printed circuit board is mounted to a metal bracket that is suitable for
either horizontal or vertical orientation. Input and output connections are accessible via screw
type terminal strips, fast-on terminals, and a .100 center connector.
TECHNICAL DESCRIPTION
Model TC-136 is capable of operating from an input supply voltage of 12 through 28 VDC, common
to many available thermoelectric modules. The self-contained MOSFET output devices deliver load
currents from 0.1 to 25 amperes (NOTE: consult appropriate installation instructions for power
supply and heat sinking requirements for high current operation). This unit will control total load
power up to 680 watts with a finite temperature resolution of 0.05°C.
The output signal to the thermoelectric module is Pulse Width Modulated and is PC selectable for
either 675 Hz or 2700 Hz operation. Pulse Width Modulation averages the amount of energy
provided to the module and reduces the extreme temperature excursions that are experienced
with an “on / off” system. This tends to extend the life and reliability of the thermoelectric devices.
The PWM control scheme affords control accuracy to within ±0.05°C. at the control sensor.
The controller tuning structure allows designation of a variety of control features. The computer set
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APPENDIX A
T
roubleshooting Communications Port
Error Message
Cause
Solution
Comm Port T
imeout
No power to TC-136
Apply power to TC-136, review
Customer Drawing for proper hookup.
Comm Port T
imeout
W
rong Comm Port Selected
Check Computer hardware settings
and set to the correct Comm Port.
Comm Port T
imeout
Incorrect wiring of the Comm Port
to the Computer
.
Check for the correct wiring from
JP3 to the Computer
.
Comm Port Open Error
No Comm Port available at this
port setting
Check Computer hardware setting
and set to the correct Comm Port.
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