Black Box IC026AE-R2, IC026A-R2 manual Peripheral Operation, Peripheral-Mode Operation

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CHAPTER 5: Peripheral Operation

5.Peripheral Operation

5.1Peripheral-Mode Operation

This mode of operation is useful in interfacing a serial device, such as a serial printer, plotter or instrument, to an IEEE controller. Data which is sent by the IEEE controller to the interface converter is buffered and transmitted out its serial port. Data received from the serial device is buffered by the interface converter until read by the IEEE controller. The interface converter can buffer approximately 32,000 bytes of data from both the IEEE input and the serial input.

The interface converter will refuse to accept more data from the IEEE controller when its buffer memory is full. It does this by preventing completion of the bus handshaking sequences. It will also request that additional serial data not be sent by negating its Request To Send (RTS) output or by transmitting the X-OFF ASCII character. The serial handshake used depends on the handshake selection (see Chapter 3).

5.2 Serial and IEEE Input Buffers

Memory in the interface converter is dynamically allocated for the serial input and IEEE input buffers. This allows for the most efficient partitioning of memory for any given application.

At power on, or device clear, each buffer is allocated a 128-byte mini-buffer or queue. When the serial input (or IEEE input) requires more buffer space, additional queues are allocated. When a queue is empty, it is released from the input buffers so that it may be re-allocated wherever it is required.

There are approximately 250 available queues for a total of 32,000 bytes of buffer (character) space. Queues are continually allocated and released as required by the serial and IEEE input. Of the 250 available queues, 240 are issued without regard to controlling the receipt of additional serial or IEEE input data.

When the serial input buffer requests one of the last 10 queues (in other words, when there are 1280 character locations left), it signals the serial host that it should stop sending data. This is accomplished by either unasserting RTS or issuing “X-OFF,” depending on which serial handshake control has been switch selected.

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Contents RS-232↔IEEE Interface Converter RS-232↔IEEE 488 Interface Converter Trademarks Used in this Manual RS-232↔IEEE 488 Interface Converter NOM Statement RS-232↔IEEE 488 Interface Converter Contents RS-232↔IEEE 488 Interface Converter Contents Specifications IEEE-488 InterfaceSerial Interface General SpecificationsDescription IntroductionAbbreviations Getting Started ConfigurationInspection Serial PortSW3 Serial Port Settings Switch SW1 Selecting the Serial Baud Rate Switch SW1 Selecting the Serial Word Length Data Bits Switch SW2 Selecting the Serial Parity Switch SW1 Selecting the Serial Handshake Selecting Terminator Substitution Switch SW2 Selecting the Serial TerminatorSwitch SW3 Selecting the Ieee Bus Terminator Selecting the ModeSelecting the Ieee Address 10. Switch SW2 Selecting the ModeFeature Selections Serial Interface 15. Selecting RS-232 or RS-422 Signal Levels TxD Transmit Data-Output-Pin RxD Receive Data-Input-PinClear To Send-Input-Pin Request To Send-Output-PinGnd Ground-Pin Vtest Test Voltage-Output-Pin+RxD Receive Data Plus-Input-Pin +TxD Transmit Data Plus-Output-PinRTS CTS DSR RTS CTS GeneralGetting Started Controller-Mode Serial to Ieee Operation Controller OperationSerial and Ieee Terminator Substitution Ieee Address Selection Talk-Back FeaturesSwitch SW1 Enabling or Disabling Talk-Back on Terminator Switch SW2 Enabling or Disabling Talk-Back on Timeout SP1PA1000,1000PDPA1000,6000PUSP0 7470APlotter Applications A PC-Based Graphics System SW3 MacPlot Configuration Screen Setting the Internal DIP Shorting Jumper for RS-422 SW3 Printer Applications Peripheral Operation Peripheral-Mode OperationSerial and Ieee Input Buffers Ieee Data Transfers Controlled BUS Data Transfers DIO8 Ieee Input Buffer not Empty Serial-Poll Status-Byte RegisterNot Defined-Always RsvSerial Input Buffer not Empty Ieee Input Buffer FullIeee 488 Bus Implementation Use of Serial and Bus TerminatorsUntalk UNT SW3 View for Ieee Address Selection Ieee 488 Primer HistoryGeneral Structure RS-232↔IEEE 488 Interface Converter DMM Send It to My AddressBus Management Lines Data Valid DAV Handshake LinesData Lines Multiline CommandsTalk Address Group TAG More on Service Requests Serial Poll Address Device Part Number Function Theory of OperationComponent Layout of the Interface Converter’s Motherboard Board LayoutRED BLK CLS Appendix A. Sample Dumb-Terminal ProgramSOH Multiline MessagesAscii Character How To Read the ChartDIO1 DIO2 DIO3 IndexIndex SW1 Copyright 1998. Black Box Corporation. All rights reserved
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