Irda Data Protocols Supported; Physical Signal Layer(Phy); Irlap - DCA Intertel s’print BT User Manual

2.3.1 IrDA DATA PROTOCOLS SUPPORTED

The printer supports these required IrDA standard protocols:
• Physical Signaling Layer(PHY)
• Link Access Protocol(IrLAP)
• Link Management Protocol/information Access Service(IrLMP/IAS)
The printer also supports some of the optional protocols for IrDA data. The
optional protocols that the printer implements are:
• IrCOMM

2.3.1.1 Physical Signal Layer(PHY)

The printer provides the following Physical Signal Layer specification
support:
• Bi-directional communication
• Data Packets are protected by a CRC-16-bit CRC for speeds up to
38400 kbaud
• Data communication Rate
-9600 baud minimum data rate (with primary speed/cost steps of 38400
baud)
• Communication Range
• Continuous operation from contact to at least 1 meter (typically 2 meters
can be reached), all the same it's possible in a low power devices reduce the distance
at least 20 cm.

2.3.1.2 IrLAP

The IrLAP protocol provides:
• Management of communication processes on the link between devices.
• A device-to-device connection for the reliable, ordered transfer of data.
• Device discover procedures.
• Hidden node handling.
Figure 2-6 identifies the key parts and hierarchy of the IrDA protocols. The
bottom layer is the Physical layer, IrPHY. This is the part that converts the
serial data to and from pulses of IR light. IR transceivers can't transmit and
receive at the same time. The receiver has to wait for the transmitter to finish
sending. This is sometimes referred to as a "Half-Duplex" connection. The
IR Link Access Protocol (IrLAP) provides the structure for packets or
"frames" of data to emulate data that would normally be free to stream back
and forth.
Figure 2-7 shows how the IrLAP frame is organized. The frame is
proceeded by some number of Beginning of frame characters,(BOFs). The
value of the BOF is generally 0xC0, but 0xFF may be used if the last BOF
character is a 0xC0. The purpose of multiple BOFs is to give the other
station some warning that a frame is coming.
The IrLAP frame begins with an address byte ("A" field), then a control
byte("C" field). The control byte is used to differentiate between different
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