In order to test the unit in interactive mode, you need a PC with a COM port running a dump terminal program, e.g. hyper terminal, tera term, etc. Then you need to setup the terminal according to the setting of the proximity card reader unit, i.e. communication speed and framing structure. For simplicity, we suggest to use one of the ASCII format, i.e. format 0, 1 or 2. After connecting the antenna, straight through RS232 cable and power supply to the unit, a character string ("RST" + LF + CR) will be sent to the host in order to notify the unit is just powered up and ready to operate. Whenever a proximity card is placed over the antenna, the card code will be sent to the host using the programmed speed and format. If the BEEP option is on, a beep sound can be heard. If the MODE option is on, the card code will be sent once to the host only until the card is moved away and returned again. While the MODE option is off, the card code will sent to the host continuously until the card is moved away. An input contacts is provided, if it is shorted, a character string ("PO" + LF + CR) will be sent to the host. While it is released, a character string ("PF" + LF + CR) will be sent to the host. In order to control the state of the RED led,Yellow led and the buzzer, the following commands can be used. To turn on the yellow led, sent two characters, ~R (0x7e, 0x52) to the unit. To turn off the yellow led, sent two characters, ~r (0x7e, 0x72) to the unit. To turn on the Red led, sent two characters, ~L (0x7e, 0x4C) to the unit. To turn off the red led, sent two characters, ~l (0x7e, 0x6c) to the unit. To turn on the buzzer, sent two characters, ~B (0x7e, 0x42) to the unit. To turn off the buzzer, sent two characters, ~b (0x7e, 0x62) to the unit. To just make a beep sound, sent two characters, ~0 (0x7e, 0x30) to the unit. To read back the states of the leds, buzzer and the input contacts, we can issue the query command by sending two characters, ~? (0x7e, 0x3f) to the unit. It will respond [S][s1][s2][s3][s4]+LF+CR, where S (0x53) represents status response; s1 is the state of the input contacts, H for shorted and L for opened; s2 is the state of the red led, H for lite and L for dim; s3 is the state of the yellow led, H for lite and L for dim; s4 is the state of the buzzer, H for sounding and L for silent.

The unit make use of an highly integrated module MS232 which is the heart of the unit providing all the functionalities. By adding small amounts of surrounding components, the complete proximity card reader unit is built. U1 is the regulator for the unit. U3 is used as the level shifter in order to interface to the RS232 link. By writing simple application software on the PC side, the unit can be used for attendance application, restricted access controlling, etc.

PCB LAYOUT