Signal Consulting, LLC  Model Si25NeTEPTC1-12B-50V-20A

Networkable, Thermo-Electric (TE), Proportional, 12-Bit, Temperature Controller with RS232 Serial Port, Integrated Heat-Sink, and with Optional LCD Port, PWM B-Chip

Si25NeTEPTC1-12B-50V-20A Features: Two User Selectable Proportional Temperature Controller Grids are used  to accommodate a wide range of Thermal Loads (G8 for small loads and G9 for large loads). Efficient H-Bridge is used for Bidirectional Current Control. 12-Bit Temperature Control in the -250C to +1020C Range with 0.0650C  steps. Set-Temperature is Adjusted ASCII Commands in 0.10C Steps. Digital Thermometer with 1/20C Accuracy,  0.6250C Resolution   12-Bit Proportional Temperature Control:  Two user selectable control grids, one for heavy and one for light  thermal loads. Each Control Grid (G8 or G9) uses Sixteen non-uniformly spaced temperature levels (centered at the set-temperature value) with eight PWM duty-cycle values to control the temperature in 0.06250 C steps.  Networkable RS232 Port: For Set-Temperature Input, and for Measured Temperature Output. Up to 16 Boards can be interconnected to form a 3-wire Local Area Network, LAN. High Power-Efficiency: 98.5% typical, at 50V and 20A Optically Isolated Control Signals On Board: Filter Capacitors VTS diodes Four 60A Power MOSFETs Bicolor LED Indicator,  (Red=Hot, Green=Cold) Voltage Requirement: A single DC Source Voltage (unregulated ) with any voltage value from 9V to 50V (for Vp)   Si25NeTEPTC1-12B-50V-20A Spec Sheet  (PDF)

The Si25NeTEPTC1-12B-50V-20A is a 50V 20A, microprocessor based, closed-loop, Networkable, Thermo-Electric, Proportional, 12-Bit, Temperature Controller board that heats or cools a thermal-zone. The temperature is measured with a 12-bit digital sensor and proportionally controlled with 0.0625⁰C steps in the -25⁰C to +102⁰C range.  An efficient high-power H-bridge controls the current (in the 0 to +/- 20A range) to Peltier type Thermo-Electric (TE) cells, functioning as a bidirectional heat-pump. By proportional control, we mean that the amount of correction used in the closed-loop is proportional to the difference between the set and measured temperature values. Two user selectable proportional control grids G8 or G9 are used to control a wide range of thermal loads. Grid G8 is used for small loads (selected when J2 is installed) and G9 is used for large loads (selected when J2 is open). Each control grid consists of sixteen non-uniformly spaced temperature levels (centered at the set-temperature value) with eight PWM duty-cycle values are used to control the temperature in 0.0625⁰ C steps. The temperature overshoots and oscillations (“hunting”) are limited to approximately + or - 0. 5⁰C. The temperature is sampled at approximately 1Hz rate and the control-loop/display is updated with the same rate.  An onboard microprocessor measures and controls the temperature; monitors the user inputs; and drives a 2 line x 20 character LCD. A small 12-bit digital thermometer, Signal’s part number Si24DTsens-12B  (connected to port CN3 and uses the Dallas Semi., DS18B20 sensor) is used to measure and control the temperature in the -25⁰C to +102⁰C range, with ½⁰ C accuracy. Because this sensor is digital, it is virtually immune to noise and loading; ideally suited for remote sensing. This sensor uses a unique “1-wire interface” (with parasite power mode) that requires only 2-conductors for reliable remote (typical length of 20 meters) temperature sensing. As the name (Ne, Networkable) implies, the desired set-temperature is selectable -25⁰C to +102⁰C range, with 0.1⁰ C steps; using ASCII command strings, obtained from the RS232 Network Port, CN6; or it can changed by using external UP/DOWN keys connected to NC4. The RS232 data format and the Local Area Network (LAN) commands are described on the next page. A “Kill-Switch” (connected to J1) is used for emergency TE-off (switch open=TE-Cell on, Switch closed=TE-Cell off with zero current, as shown on the application drawing below). An optional LCD port (with HITACHI HD44780 Interface Standard) is provided for display of the Set and Measured temperature data. The 2 line x 20 character LCD can be ordered from Signal under the part number of Si24LCD2L20CH  (2x20 display with 8” ribbon cable and 14-pin connectors and with back-light). A bicolor LED is used to monitor the TE cell (or load) voltage (Red = Heat, Green = Cold). This board operates with a single unregulated voltage source (9V to 50V range). A small (3.0”x3.0”x0.8”), integrated, Aluminum heat-sink is used to operate at 1000W power level. Higher power-levels can be achieved with more efficient heat-sinks. Typical applications are: Peltier Effect TE Coolers, Heat Pumps, etc.

A Typical Application of the Si25NeTEPTC1-12B-50V-20A

In this 12-bit, closed-loop, proportional temperature control application, the Set-Temperature is adjusted  by command strings derived from a Personal Computer (PC) using the Microsoft “Hyper Terminal” program (or any-other ASCII controller) operating at 9600 Baud, 1 start-bit, 8 data-bits, 1 stop-bit, No parity-bit. The Peltier type Thermo-Electric (TE) cell is functioning as a bidirectional heat-pump; operating with 12VDC (unregulated) at 20A max. TE cells can be purchased from Melcor Corp. Trenton, NJ 08648 USA, WEB: www.melcor.com. The temperature of the enclosed and insolated Hot/Cold Environment is measured with the Dallas Semi. DS18B20 (in TO-92 casing) Digital Thermometer, Si24DTsens-Spec1-DS18B20.This sensor can be purchased from Signal Consulting, LLC as Si24DTsens-12B (DS18B20 with 12” leads and connector). The optional LCD module can be ordered from Signal using the part number of Si24LCD2L20CH  (2x20 display with 8” ribbon cable and 14-pin connectors, and with back-light).  Warning:  The connecting wires to the Load and the Power Supply must be heavy gage copper wire (#12 AWG or heavier) to handle the rated current level. In addition, these heavy gage wires act as a heat sink, protecting the board from overheating.

Command Format and Local Area Network (LAN) for the Si25NeTEPTC1-50V-20A

Each board has a unique, 4-bit, none-volatile, Node-Address (ranging from 0,1….9, A..F); this can be changed by a LAN command (the factory default address is 1). The board uses a modified version of the RS232 serial-data communication standard, where the output-voltage (on pin I2, CN6) ranges from 0 to +5V (rather than the usual -12V to +12V). In addition, this output pin is normally an open circuit and it will only output a serial TTL binary bit-stream when properly referenced by its Node-Address. The serial data input-voltage (on pin I1, CN6) has the standard range of -12V to +12V. The serial data-format is: 9600 Baud Rate, 1 Start-Bit, 8 Data-Bits, 1 Stop-Bit, and no Parity-Bit.

These features allow the creation of a Local Area Network (LAN) with up to 16 nodes (boards). A typical 3-wire LAN with “Star Topology” is shown below. Note that the control lines (G, I1, I2) with the same name are connected together (or the boards are connected in parallel) and driven by an ASCII controller (or PC), equipped with an RS232 serial port, operating at 9600 Baud rate.

Command Rules:

1.  All Commands are ASCII character strings (Chars.).  An ASCII string is denoted here with Bold Red Letters (Characters).

2.  Each string is terminated by a Carriage Return Character, (CR). The only exception is the N command.

3.  Upper-Case Letters are used for Output Commands; and Lower-Case Letters are used for Input Commands.

4. The 1^st Char. in a string is either capital N or a Hex-Digit Node Address (0, to F). If the 1^st Char. is an N, it denotes a query to all boards on the LAN to output their Node Address and Program Name.

5. If the 1^st Char.  is a Hex-Digit (0,1..,9,A,B,C,D,E,F), it directs the rest of the command string to the board that has this address.

6. The 2^nd Char. in the string is the Command Character that operates on the addressed board.

7. The 3^rd, 4^th, 5^th and 6^th Chars. represents the value of the input data. Where + denotes positive Set-Temperature values; and - denotes negative Set-Temperature values.

8. The last Char. in the sequence is always the string terminator, (CR).

Command Examples:

Ex#1.  Com. String:  N     Action: All boards on the LAN will output their Address and Program Name.

Ex#2.  Com. String:  1n5(CR)          Action: Change Board 1 Address in EPROM from 1 to 5.

Ex#3.  Com. String:  1T(CR)           Action:  Board 1 outputs its Set and Measured Temperature.

Ex#4.  Com. String:  2t25(CR)        Action: Change Board 2 Set-Temperature to +25.0C.

Ex#5. Com. String:  2t+25.0(CR)    Action: Change Board 2 Set-Temperature to +25.0C.

Ex#6.  Com. String:  2t-25(CR)       Action: Change Board 2 Set-Temperature to -25.0C.

Availability: We usually ship in 2-3 business days.

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