Signal Consulting, LLC 

Model Si25NeBdMC1-50V-20A

Networkable, Bidirectional, Open-Loop, 50V 20A, Motor Controller with RS232 Serial Port, Integrated Heat Sink and with 20kHz or 5kHz PWM





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Si25NeBdMC1-50V-20A Features:

Efficient H-Bridge: for Bidirectional Current Control
Directional Control: with ASCII Command-Characters
Max. Current for 5 sec : 40A with the Integrated Heat-Sink
Max. Continuous Current: 20A with the Integrated Heat-Sink

Two User Selectable PWM Frequency: 5KHz or 20kHz

Two User Selectable Motor Acceleration/Deceleration Modes:  Using Jumper on Port J1.

 Networkable RS232 Port: Used for Set-Duty-Cycle Input, and for Measured Duty-Cycle Output. Up to 16 Boards can be interconnected to form a 3-wire Local Area Network, LAN.

Voltage Requirement: VC (from pin +C to pin - P): 9V to 30V DC at 0.1A, and for VP (from pin +P to pin -P) 9V to 50V at 20A, both unregulated DC voltages. For low-voltage applications (9V to 30V) a single DC power supply can be used by connecting pin +P and pin +C together.

Alarm Kill Switch on J1: A normally open switch (or an Open Collector npn Transistor) can be connected to jumper port J1 (as shown below), J1 Open=Normal operation, J1 Short=Load (TE Cell) is open.

Sampling Rate: All control lines are sampled approximately at 200Hz rate.

High Power-Efficiency: 98.5% typical, at 50V and 20A
Optically Isolated Directional Control Signals
Power Semiconductors: Four 90A Hex-MOSFETs
Overall Dimensions: 3.95" x 3.7" x 1.9" (100 x 94 x 48mm).
Components Type: 100% Solid State, NO Relays

On Board:
Filter Capacitors
VTS diodes
Snubber Circuit
  Bicolor LED Indicator,  (red=forward,  green= reverse)


 For Details, Download the  Si25NeBdMC1-50V-20A-6B1   Manual (PDF)


 The Si25NeBdMC1-50V-20A is a 50V 20A, networkable, microprocessor based, high-power, Bidirectional, Motor Controller that uses one or two DC power supplies to control the speed of a DC motor in forward or reverse direction. 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), monitors the user inputs and controls the RS232 Network Port. The PWM carrier frequency is user selectable by the jumper J2, 5kHz when J2 is open and 20kHz when J2 is short. This high frequency PWM rate insures a quiet motor environment. The user can choose between slow or fast motor acceleration/deceleration modes by short-circuiting or open-circuiting the pins labeled J3.  The slow mode, with rise-time/fall-time of 0.5s, is selected by open-circuit (J3 jumper NOT installed); while the fast buildup mode, with rise-time/fall-time of 0.05s, is selected by shorting the J3 pins (J3 installed). The jumpers J2 and J3 are examined only at power turn-on. All control lines are sampled approximately at 200Hz rate. As the name (Ne, Networkable) implies, the required motor speed (PWM pulse-duration and direction) is variable from 0 to + or -100% in 0.83% steps by using ASCII command strings, inputted  on the RS232 Network Port. 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 motor-stop (switch open=Motor Runs, Switch closed=Motor Stop with zero current, as shown on the application drawing below). All control inputs are optically isolated or zener-diode protected. A bicolor LED is used to monitor the motor (or load) voltage (Red = Forward, Green = Reverse). A small (3.95”x3.7”x0.55”), integrated finned heat-sink is used to operate at 20A current levels. Higher current-levels (25A or 1200W) can be achieved with more efficient heat-sinks. Please click on this link and read the Board Mounting Instructions and Heat Sink Selection Guide. A flashing green LED indicates that the microprocessor is operating properly. This board operates in a wide voltage-range (9V to 50V) at max. continuous load-current of 20A. Typical applications are: Bi-directional DC Motor-Speed Controller, Proportional Valve-Coil Controller, DPDT Solid State Relay, etc. This board can be configured and programmed to perform efficiently in many customized applications. 

A Typical Application of the Si25NeBdMC1-50V-20A

 In this open-loop application, the motor speed (in forward or reverse direction) 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.  Warning:  The connecting wires to the Load and the Power Supply must be heavy gauge copper wire (#12 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 Si25NeBdMC1-50V-20A

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, 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 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 a 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 and 6th Chars. represents the value of the input data. Where + numbers denote forward rotational values; and - numbers denote reverse rotational values.

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:  1D(CR)        Action:  Board 1 outputs its Set and Measured % PWM (0,..100.0%).  

Ex#4.  Com. String:  2d25(CR)      Action: Change Board 2 PWM to 25.0% in Forward Direction.

Ex#5. Com. String:  2d+25.0(CR)   Action: Change Board 2 PWM to 25.0% in Forward Direction.

Ex#6.  Com. String:  2d-25(CR)     Action: Change Board 2 PWM to 25.0% in Reverse Direction.

Ex#7. Com. String:  2d-25.0(CR)    Action: Change Board 2 PWM to 25.0% in Reverse Direction.

Ex#8.  Com. String:  1M(CR)       Action:  Board 1 outputs its Set and Measured Motor Value (0,..120).

Ex#9. Com. String:   2m+60(CR)   Action: Change Board 2 Motor Value to 60 = +50% PWM, in Forward Direction.

Ex#10.  Com. String:  2m-60(CR)    Action: Change Board 2 Motor Value to -50 = -25.0% PWM in Reverse Direction.

We recommend that you use approximately 25msec delays (or longer) between characters when inputting a command string (“1d..(CR)”,“1m..(CR)”, “1D(CR)” or “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 -120,….,0,….+120. The positive values are used for forward speed control, while the negative Motor Values are used for reverse 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 d command uses a variable input format (integer or fractional) % PWM Motor Values, ranging from -100.0,…., 0.0,….+100.0. The positive % PWM Motor values are used for forward speed control, while the negative % PWM Motor Values used for reverse speed control.

Note3: The d command is subject to +, - 0.833% “round-off” errors, while the m command is NOT!!!

The d command provides variable decimal display format (+ - 00.0%,…100.0%).

 While the m command provides decimal integer display format (0,…+, - 120).

Network Configuration:

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

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 below. Before you build your network, click on this blue link and read this Application NoteSig-Note on Configuring a LAN-2 .

Si25NeBdMC1-50V-20A,  Networkable Bidirectional Motor Controller Board
Price $249.00

Note: If Buying the Si25NeBdMC1-50V-20A, it is recommended to buy one or more Network Accessories .

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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