Ircomm; 3-Wire Raw And Irlpt In Detail; How 3-Wire Raw And Irlpt Differ - DCA Intertel s’print BT User Manual

2.3.1.5 IrCOMM

IrCOMM provides the method to support serial and parallel port emulation.
This is useful for legacy COM applications, such as printers and modem
devices.
The IrCOMM standard is simply a syntax that allows the primary device to
consider the Secondary device as a serial device. IrCOMM allows for
emulation of serial or parallel (printer) connections of various capabilities.
The printer supports the 3-wire Raw service class of IrCOMM and IrLPT.
Other service classes supported by IrCOMM are shown in Figure 2-8

2.3.1.5.1 3-Wire Raw and IrLPT in Detail

3-Wire raw and IrLPT may be used to emulate either serial or parallel ports
in cases where a single exclusiveconnection is satisfactory. They can emulate
both port types because there is no control channel, and therefore no
information about the non-data circuits of either type is carried - only the data
normally flowing through thedata circuits is emulated. If data transfer is all a
port needs to function, then 3-Wire raw or IrLPT may be fine.
(Fig.2.8)

2.3.1.5.2 How 3-Wire raw and IrLPT differ

3-Wire raw and IrLPT are two names for the same COMM emulation service.
IrLPT was built into some commercially available devices before this
IrCOMM specification was complete, and is included here for compatibility.
There are two differences between 3-Wire raw and IrLPT:
• IrLPT has a fixed definition and purpose - it is for printing only. IrCOMM 3-
Wire raw can be used forboth printing and non-printing tasks
• 3-Wire raw uses an IAS entry with classname IrDA:IrCOMM and at least
two parameters. Its IAS definition may be modified or extended over time.
IrLPT has classname IrLPT, only one parameter, and the IAS definition
isfixed. IAS entry formats are defined in the next section.
Beyond these two distinctions, 3-Wire raw and IrLPT are the same.
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