DLCSDLC Programming Interfaces

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The synchronous data link control (SDLC) device manager (DLCSDLC) conforms to the generic data link control (GDLC) guidelines except where noted.

Additional structures and definitions for DLCSDLC can be found in the /usr/include/sys/sdlextcb.h file.

Note: The GDLC entry-point prefix dlc is replaced with the sdl prefix to denote DLCSDLC device manager operation.
Item Description
sdlclose DLCSDLC is fully compatible with the dlcclose GDLC interface.
sdlconfig DLCSDLC is fully compatible with the dlcconfig GDLC interface. No initialization parameters are required.
sdlmpx DLCSDLC is fully compatible with the dlcmpx GDLC interface.
sdlopen DLCSDLC is fully compatible with the dlcopen GDLC interface with the following conditions:
  • Single-physical unit (PU) mode allows only one open per port. The open can come from either an application or kernel user, but multiple users cannot share the same port. Single-PU mode is entered by issuing the open without an extension, or by issuing an extended open with the maxsaps (maximum service access points) field set to a value of 0 or 1. Single-PU mode is the default.
  • Multiple-PU mode allows multiple processes to open a secondary port. Multiple-PU mode is entered by issuing an extended open with the maxsaps field set to a value greater than 1.
Note: Only one user process is allowed to open a primary port.
sdlread DLCSDLC is compatible with the dlcread GDLC interface, with the following conditions:
  • Network data is defined as any data received from data communication equipment (DCE) that is not specific to the SDLC session protocol. Examples are X.21 call-progress signals or Smartmodem call-establishment messages. This data must be interpreted differently, depending on the physical attachment in use.
  • Datagram receive data is not supported.
sdlselect DLCSDLC is fully compatible with the dlcselect GDLC interface.
sdlwrite DLCSDLC is compatible with the dlcwrite GDLC interface, with the exception that network data and datagram data are not supported in the send direction. Network data such as X.21 or Smartmodem call-establishment data is sent using the DLC_ENABLE_SAP ioctl operation.
sdlioctl DLCSDLC is compatible with the dlcioctl GDLC interface, with conditions on the following operations: