Signal Consulting, LLC 

 Model Si50NeUdMC1-120V-32A

Single Channel, Open-Loop, Networkable, Unidirectional, 120V-32A DC Motor Controller with Integrated Finned Heat Sink, 5kHz or 20kHz PWM, T-Chip





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 Si50NeUdMC1-120V-32A Features:
Power Semiconductors: Two 200A MOSFETs
Max. Continuous Current: 32A with Finned Heat-Sink (as shown).
Max. Current for 5 sec: 100A with Proper Heat-sinks
Board's Size: L=3.2", W=2.6",H=1.9" (8.12 x 6.6 x 4.82cm).
Overall Size (with Large Heat Sink): L=5.9", W=3.7",H=2.4"

Components Type: 100% Solid State, NO Relays  

  A single DC Motor or Load is controlled  by a Pulse Width Modulator (PWM).

 PWM carrier frequency is  user selectable with a jumper, 20kHz when the jumper is open and 5kHz when closed.

  The average Load-Voltage is adjustable from 0V to 120V (or to Vp) in 120 steps  using the RS232 input commands .

  User can choose between slow or fast motor acceleration/deceleration modes.

High Power-Efficiency: 98.5% typical, at 120V and 32A

On Board:
Filter Capacitors
VTS diodes
Snubber Circuit Ready
Voltage Requirement:
A single DC Source Voltage (unregulated ) with any voltage value from 35V to 120V (for Vp)


   For Details, Download the  SiNeHyUdMC1-120V-32A-3T6    Manual


The Si50NeUdMC1-120V-32A is a 120V, 32A, microprocessor based, Single, Open-Loop, Networkable, Unidirectional, Motor-Controller board that uses 5kHz or 20kHz pulse-width modulation (PWM) to efficiently control the speed of a brush type DC motor (or load  current ) in the 0 to 3840W power range, and in 32W steps. An onboard microprocessor generates a 5kHz or 20kHz PWM carrier signal, controls the load-power (or motor speed), controls the load-current rate (or motor acceleration and deceleration), updates the display, monitors the user inputs and controls the RS232 Network Port. The PWM carrier frequency is user selectable by the jumper CN4, 20kHz when CN4 is open and 5kHz when short. The high frequency PWM rate provides a smooth speed control and provides a quiet motor environment. As the name (Ne, Networkable) implies, the desired motor speed (or PWM duty-cycle) is acquired from an RS232 port; and duty-cycle is variable from 0 to + or -100% in 0.83% steps. The Local Area Network (LAN) and the RS232 Protocol is described below. A normally open switch (or an Open Collector npn Transistor) can be connected to jumper J1 (as shown below), J1 Open=Normal operation, J1 Short=Load is open. The active pin on J1 is pulled to +5V through a 4.7k Ohm resistor, while the other pin (G) is at ground.  The user can choose between slow or fast motor acceleration/deceleration modes by short-circuiting or open-circuiting the pins labeled J2.  The slow mode, with rise-time/fall-time of 0.5s, is selected by shorting J2 (J2 jumper installed); while the fast buildup mode, with rise-time/fall-time of 0.025s, is selected by leaving J2 open. An LCD port CN3 (with 9600 Baud RS232 Interface Standard) is provided for display of the Set and Measured Motor data. The LCD can be order Signal under the part number of Si14LCD2L16CH-3PC  (2-Line by 16-Char display with 12” cable and 3-pin connectors, and with back-light). An onboard LED (red) is used to monitor the load-voltage. A small (3.0”x4.0”x1.0”) finned heat-sink is provided to operate 1500W power level (or at 120V and 32A) Higher current level levels (50A at 120V or 6000W) can be achieved with more efficient heat-sinks (5” x 5” x 1.5” finned heat sink). This board requires a single 35V to 120V DC unregulated power source at a 0A to 32A current range to operate normally. Typical applications are: DC Motor-Speed Controller, Light-Dimmer with variable delay, Power Amplifier, SPST Solid State Relay, etc. This board can be configured and programmed to perform efficiently in many customized applications.

A Typical Application of the SiNeHyUdMC1-120V-32A

In this open-loop speed control application, the motor speed (or PWM pulse-duration) is adjusted with an external controller or PC computer using the Hyper Terminal program; controlling the duty-cycle of the motor  from 0% to 100%  in 0.833% steps. The DC Motor can be purchased from: Bodine,, and An inexpensive, unregulated DC power supply is shown in this application drawing.  A wide variety of linear and switching power supplies can, also, be used with this board. Consult the most recent catalog on to purchase these power supplies. Warning:  The connecting wires to the Motor and the Power Supply must be heavy gauge copper wire (#10 AWG or heavier) to handle the rated current level. In addition, these heavy gauge wires act as a heat sink, protecting the board from overheating.

Command Format and Local Area Network (LAN) for the Si50NeUdMC1-120V-32A

Each board has a unique, 8-bit, ASCII, none-volatile, Node-Address ranging from 1….9, A..Z, a,…z (or a total of 61 Units can be networked ).The address 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, CN5) 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, CN5) 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 61 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 # command.

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

4. The 1st Char. in a string is either ASCII # or a Node Address (1, .,9,A..Z, a,..,z). If the 1st Char. is an #, it denotes a query to all boards on the LAN to output their Node Address and Program Name.

5. If the 1st Char. is an ASCII (1..,9,A,..Z, a,…,z), it directs the rest of the command string to the board that has this address.

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

7. The 3rd, 4th, 5th Chars. represents the value of the input data.

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

Command Examples:

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

Ex#2.  Com. String:  1u5(CR)      Action: Change Board 1 Address in EPROM from 1 to 5.

Ex#3.  Com. String:  1M(CR)       Action:  Board 1 outputs its Set and Measured Values (0,..120).  

Ex#4. Com. String:   1m120(CR)    Action: Change Board 1 Load Value to 120 = 100% PWM.

Ex#5.  Com. String:  2m60(CR)     Action: Change Board 2 Motor Value to 60 = 50% PWM.

We recommend that you use approximately 25msec (or longer) delays between characters when inputting a command string (“1m..(CR)”, “1M(CR)”) to this controller board. 

Occasionally, a transient character may be captured and buffered by one more board on the LAN, this transient character can be cleared by sending one  or more (CR) prior to a valid command string.

Note1: The m command inputs decimal integer Motor Values, ranging from 0,….+120. The positive values are used for forward speed control. The PWM duty-cycle varies linearly with the input values; 0 value is equal to 0% PWM, while 120 value is equal to 100% PWM.

Note2: The m command is NOT subject to round-off” errors!!!

Note3: The last set value entered with the m command or with the Up/Down keys is saved when the power is turned off, and this value is restored when the power is turned back on.

 Response to Commands on Output Line I2:

The response to a "1M(CR)" command is an ASCII character string (or a line of characters). Each string is terminated with carriage return and line feed characters. An example is shown below: 

N=1  SM=120  MM=120

 Note that there are two space characters between 1 and S; and there are two space characters between C and M. The length of this character string is 22, including carriage return and line feed characters  (not shown in this example).  Where N=1 is the node (or unit) address of the board (can be changed with the u command), SM=120 is the last Set-Motor Speed Value (entered with the m command), and MM=120 is the current Measured-Motor Speed Value. 

 Each character string (line) is a continuous stream of ASCII characters with an occasional pause (or delay) between characters. This delay is approximately 1msec.

The on-board microprocessor provides the bus arbitration, required to avoid data collisions on the 3-wire LAN bus.

Network Configuration:

The  Si..Ne.. boards can be arranged in many Local Area Network (LAN)  topologies: Star, Daisy-Chain, etc.  You may create your own network or you may order one or more of the Network Cable Assemblies listed in the Application Note.   Before you build a network, we recommend that you click on this blue link and read this Application Note:  SigNote on Configuring a LAN-2 .

    Si14LCD2L16CH  2-Line by 16-Character LCD Format on Port CN3

 A 9600 Baud serial port (CN3) with 5V RS232 Interface standard is provided for optional display of the Motor data.

    Line#1:    SM=120    MM=120         or Set Motor (SM) and Measured Motor (MM)  PWM are 100%.

 Line#2:    N=1   B=xxxxxxxxx         or N=Node Address,   B= Commands Entered.

 For more information on the Display, please click on this link: (Si14LCD2L16CH-3PC). 
Si50NeUdMC1-120V-32A, Networkable Unidirectional Motor Controller, 1 DC Load at 120V, 32A  
Price $259.00

Note: If Buying the Si50NeUdMC1-120V-32A, it is recommended that you buy one more accessories listed below.

Optional Si14LCD2L16CH-3PC  2 Line by 16 Character LCD with 12" long cable and 3-pin connectors.  
Price $59.00
Si25-DB9cable1 , 1m long Network Cable Assembly with 9-pin female DB9  connector.
Price $19.00
Si25-PJtoHcable-1m , 1m long cable assembly with Phone Jack and Header connector.
Price $19.00
Si25-LANhub5  , 1m long Network Cable Assembly 9-pin female DB9  connector and a “Junction-Box” with 5 Phone Jacks.
Price $39.00
Si25-LANext5  , 1m long Network Cable Assembly with 6P4c Phone Plug  connector and a “Junction-Box” with 5 Phone Jacks.
Price $29.00

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