3270 Remote Operations BSC is an IBM-standard, byte-synchronous protocol for half-duplex, multipoint links. This data link control protocol provides flow control and error detection, and guarantees the accurate exchange of information across the physical interface.

UconX Corporation has implemented the 3270 BSC protocol in a client-server environment. The entire protocol runs on the UconX family of LAN-based, multi-protocol communication servers. The UconX server attaches to your local area network to provide wide-area connectivity for all clients on the LAN.

UconX also supports 3270 BSC on various high-speed SBus, VMEbus and PCI intelligent communication controllers.

A single server or controller can support 3270 BSC operation on multiple serial links. Or, you can run other UconX protocols, such as x.25 or Asynchronous Data Transfer, on some links and 3270 BSC on others.

Features.

• Can act as a control station (transmission control unit) or a tributary station (3275 control unit).
• Conforms to the specifications for Remote Operations - BSC contained in the IBM document GA27-2749-10, IBM 3270 Information Display System Component Description.
• Supports multiple serial lines, which are independently configurable for baud rate, clock source, frame size, character encoding and other options.
• Client software in source form includes an Application Programming Interface (API), sample application programs, and, for embedded communication controllers, a host device driver.
• Supports line speeds up to 38.4K bits/second.
• LAN-based servers support UNIX and VMS client systems.
• Other UconX wide-area protocols can operate simultaneously on the same platform.
• Data transmission and reception in loopback mode can be used to verify correct installation and hardware operation.

Client API.

3270 BSC includes a simple, easy-to-use API to protocol software running on a LAN-based server or communication controller. The API provides a standard interface to the TCP/IP software or host driver. This makes application programs easily portable among client operating systems as well as the various UconX server and embedded controller platforms.

DLPI Interface Primitives.

For the interface to 3270 BSC, UconX uses a subset of the Data Link Provider Interface (DLPI), which defines a STREAMS-based message interface between a data link service provider (3270 BSC) and an application program. Applications send and receive DLPI messages, or primitives, using the UconX API.

The following primitives are sent from the application to 3270 BSC:

DL_BIND_REQ

Assigns and configures a serial link.

DL_UNBIND_REQ

Frees a previously bound serial link.

DL_CONNECT_REQ

Brings the connection to data transfer state.

DL_DISCONNECT_REQ

Disconnects an active connection.

DL_RESET_REQ

Requests transmission of an RVI.

DL_GET_STATISTICS_REQ

Requests connection statistics.

DL_DATA_REQ

Contains data to be sent as a 3270 BSC normal or transparent text block.

The following primitives are sent from 3270 BSC to the application:

DL_BIND_ACK

Indicates successful completion of DL_BIND_REQ.

DL_ERROR_ACK

Reports unsuccessful completion of a request.

DL_RESET_IND

Reports reception of an RVI.

DL_GET_STATISTICS_ACK

Provides data transfer statistics.

DL_DATA_IND

Contains data received as a 3270 BSC text block.

Statistics.

At any time, a client application can request statistical and state information for its 3270 BSC connection. The protocol software maintains detailed counts of transmitted and received messages, separated by type; and line errors, such as CRC or LRC errors, parity errors and receive overruns.

Configuration Parameters.

For each individual serial link, the UconX 3270 BSC software package allows configuration of the following parameters:

• Master or slave operation (control or tributary station)
• For a slave, control unit and device number
• For a master, list of control units/device numbers to poll, poll type (general or specific), and poll timeout
• EBCDIC with CRC16; 8-bit ASCII with CRC16; or 7-bit ASCII with LRC8 and odd parity
• Maximum block size
• Number of sync and PAD characters
• Use or ignore modem signals
• Record separator translation
• Line speed or external clocking

Ordering Information: For more information or to place an order, please contact Joseph Dohn at (619) 627-1700 or email us at sales@uconx.com . For technical questions about our products, please email us at tech@uconx.com .