Printer User Manual

Page 33
Appendix D
Infrared Data Input Option
Introduction
This appendix summarizes the operating features of the Extech MSP Series printers with built in
InfraRed Data Receiver Interface (IRD). The IRD Interface is designed for reception of IRD-
ASK format serial data and no interconnecting cables are required for data transfer.
The IRD data transfer is a one way link, in the current version of the printers. The printer has
circuitry to receive IRD-ASK data but there is no circuit allowing IRD to be transmitted back.
For reliable serial data transfer, software timing must be implemented in the IRD-ASK
transmitter. It is the transmitters responsibility to be sure the printer's 2000 Byte buffer never
overflows.
IRD-ASK Receiver Specification
The IRD-ASK receiver consists of photodiode IR detector, automatic gain control amplifier and
500KHZ bandpass filter.
The amplifier prevents saturation of the receiver if strong IR signal is applied, while the
bandpass filter rejects any IR signal without the 500KHZ carrier signal.
The Operating Characteristics of IR Receiver are summarized in TABLE 1.
Transmission Wavelength 900 to 1,050 nanometers
Modulation Frequency 500KHZ ± 50
Modulation Process Amplitude Shift Key (ASK)
Range 1 meter
Data Rate 1200 - 9,600 Bits per second/
DIP switch select baud rate and
parity.
Table 1
IR Receiver Operating Characteristic
Printer Power-up through IRD-ASK Interface
The MSP printer can be powered-up by transmitting a single character. To avoid the loss of data
during "Logic Switching", pause for 1.0 seconds before sending additional characters to the
printer.
The MSP printers have a built-in 30 second Power-Down-Timer. The timer is automatically
restarted under any one of the following conditions.
- If side panel <ON>, <FEED> or <ADVN> switch is pressed.
- If a character is received via IRD-ASK data interface.