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2. INTERFACES
9 2- DPT100-B/I/BT
2.3.1.4 Link Management-Information Access Service (LM-IAS)
Each LM-IAS entity maintains an information data base to provide:
•
Information on service for other devices that contain the IrDA standard feature (Discovery)
• Information on service for the device itself
• Remote accessing of another device’s information base
This is required so that clients on a remote device can find configuration information needed to access a
service.
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.
IrCOMM Service
Uncooked
Services
Parallel
IrLPT
Serial
3-wire Raw
Parallel
Centronics
IEEE 1284
Cooked Services
Serial
3-wire Cooked
9-wire Cooked
Supported by printer
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.
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
(Fig.2.8)