# System monitoring and fan regulation HE2661

HE2661 is a module for the activation of fans and for the monitoring of supply voltages. The module supports the monitoring of up to 4 voltages (+3.3 V, +5 V, +12 V and –12 V). A minimum and maximum value can be defined for each of these voltages.

The fan control unit is designed for 12 V fans with tacho signal. Up to 8 fans are supported. They are divided into 4 groups of 2 fans. One of 4 temperature sensors (X11-X14) can be assigned to each group. The maximum current is 1.5 A per fan. The supply voltage is 12V.

NTC temperature sensors with 33 kOhm and 100 kOhm are supported.

All current values are cyclically output on a 2-line LCD display on the module. The LCD contrast can be adjusted through the potentiometer R66.

LED H1-H6

H1 shows the status for +12 V, H2 for –12 V, H3 for +5 V, H6 for 3.3 V, H4 for the temperature and H5 for the fans. Green LEDS indicate correct operation; a colour change to red indicates an error.

Voltage supply connections X21 and X22

An M4 screw connection is provided for GND and another M4 screw connection is provided for the operating voltage +12 V.

Multi-pin connector X28

If Pin 1 and Pin 2 are connected by a jumper, the ACFAIL VME signal is generated. If Pin 3 and Pin 4 are connected by a jumper, the SYSRESET VME signal is generated.

Beeper Reset X25

The connected button connects Pin 1 and Pin 2 of the plug. An acoustic alarm signal can be reset by pressing the button.

Beeper Out X26

Serves for the connection of an acoustic signal transmitter: In the case of an error an acoustic alarm is triggered, as long as the corresponding error event was enabled in setup.

Connector X32

This plug is connected directly to the microcomputer unit (MCU). Only provided for internal use.

Error output X33

5V are present at the pins. In the case of error, the corresponding pin is connected to ground.

In System Programming (ISP)

The MCU can be programmed through the plug X31. Only provided for internal use.

Pin Assignments

Mating Connector and Pins (e. g.)

System requirements

WindowsXP with installed Microsoft .NET Framework 2.0 Release 2.0.50727.42. NET framework can be found on the Microsoft homepage and is free of charge. The fan control unit uses the FTDI chip FT232R for communication through the USB interface. In the process, it is a matter of a USB/UART interface which is responded to like a serial interface on the host computer. For this purpose, 2 drivers from FTDI must be installed:

• A. USB Serial Port Driver
• B. USB Serial Converter Driver

The minimum resolution for the screen is 800 x 600 pixels.

The settings of the required parameters for fans, temperature sensors and voltage monitoring are provided with the program FanControl.exe.

FanControl is a setup and monitoring program for Windows, which can access the fan control unit through the USB interface. This is no longer necessary for normal operation.

Commissioning

Before FanControl is called up, the fan control unit must be in operation and connected to the host computer through the USB cable (USB A/B). Then the allocated COM ports are displayed. One of these COM ports corresponds to the USB interface. They are assigned dynamically by the operating system. In most cases the COM port corresponds to the highest number of the USB interface. The connection is activated with Connect and the window shows the current values.

Important: Before the fan control unit is switched off or the USB cable is pulled out, the connection must be discontinued with Disconnect. Otherwise, malfunctions can arise.

The program window shows both actual and target values. If a value such as the minimum value for the +12 V voltage supply is changed in the window, the transfer to the fan control unit only takes place after pressing Set. Immediately afterwards, the setup used for the current operation becomes effective. It is permanently saved by pressing Save. In order to retain the current measurement values, Reload must be pressed once for an update, or Auto Reload for permanent updating. In the process, the current applicable setup is also updated.

Monitoring of supply voltages

The fan control unit supports the monitoring of up to 4 supply voltages (+3.3 V, +5 V, +12 V and –12 V). A minimum and maximum value can be defined for each of these voltages. If a value lies outside the range, an error message with error code is displayed and an acoustic signal may be issued.

Fan speed monitoring and regulation

The fan control unit is designed for 3-pin 12V fans. Up to 8 fans are supported. They are divided into 4 groups of 2 fans. One of 4 temperature sensors can be assigned to each group. If both fans from a group are connected and only one of them was selected in the checkbox, both will still receive the same supply voltage.

If no temperature sensor is assigned to a group, these fans are run with maximum voltage. The speed in rpm can be seen next to the checkbox. In case of an undercut of the minimum speed, an error message is displayed and an acoustic signal may be issued.

The speed is controlled depending on the temperature and the temperature range entered in the "Speedcontrol" dialogue field. With "Min Temp" the fan runs at a minimum speed. With "Max Temp" the fan is operated with 12 V.

The correct sensor type must be entered in the "Temp1" to "Temp4" dialogue fields.

The designation 100K/33K corresponds to the resistance value at 25°C. The temperature of the respective sensor can also be seen here. If one of the temperature sensors exceeds the targets in the "Error Temp" dialogue field, an error message is issued.

The error codes for all values are issued in the "Error" dialogue field and values beyond the tolerance are displayed in red.

Through the "Beeper Event" dialogue field it is determined whether errors have been issued through an acoustic signal transmitter.

Description of error codes:

Incorrect Parameter