Black Box IC026A-R2, IC026AE-R2 manual Switch SW1 Selecting the Serial Handshake

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RS-232↔IEEE 488 INTERFACE CONVERTER

3.3.6SERIAL HANDSHAKE

Switch SW1-5 is used to select hardware [RTS/CTS] or software [Xon/Xoff] serial handshake control.

With X-ON/X-OFF, the interface converter issues an X-OFF character [ASCII value of $13] when its buffer memory is near full. When the X-OFF character is sent, there are still more than 1000 character locations remaining to protect against buffer overrun. When it is able to accept more information, the inter- face converter issues an Xon character [ASCII value of $11]. The interface converter also accepts X-ON/X-OFF on transmit from the serial host it is communicating with. RTS/CTS serial control becomes inactive when X- ON/X-OFF is enabled. The RTS output is, however, set to an active high state. The CTS input is not used for this handshake and may be left floating (unconnected).

With RTS/CTS, the interface converter un-asserts RTS (sets RTS low) when its buffer memory is near full. When RTS is un-asserted, there are still more than 1000 character locations remaining to protect against buffer overrun. When it is able to accept more information, the interface converter asserts RTS (sets RTS high). The interface converter will not transmit data to the serial host if it detects the CTS input un-asserted (low) when configured for this hardware handshake.

The factory-default serial control is hardware, RTS/CTS.

1 2 3 4 5 6 7 8

OPEN

RTS/CTS

1 2 3 4 5 6 7 8

OPEN

X-ON/X-OFF

Switch

Side

View

DOT

Figure 3-7. Switch SW1: Selecting the Serial Handshake.

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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 Serial Interface SpecificationsIEEE-488 Interface Specifications GeneralIntroduction DescriptionAbbreviations Configuration Getting StartedInspection 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 Switch SW2 Selecting the Serial Terminator Selecting Terminator SubstitutionSelecting the Mode Switch SW3 Selecting the Ieee Bus Terminator10. Switch SW2 Selecting the Mode Selecting the Ieee AddressFeature Selections Serial Interface 15. Selecting RS-232 or RS-422 Signal Levels RxD Receive Data-Input-Pin TxD Transmit Data-Output-PinClear To Send-Input-Pin Request To Send-Output-PinVtest Test Voltage-Output-Pin Gnd Ground-Pin+RxD Receive Data Plus-Input-Pin +TxD Transmit Data Plus-Output-PinRTS CTS General DSR RTS CTSGetting Started Controller Operation Controller-Mode Serial to Ieee OperationSerial and Ieee Terminator Substitution Talk-Back Features Ieee Address SelectionSwitch SW1 Enabling or Disabling Talk-Back on Terminator Switch SW2 Enabling or Disabling Talk-Back on Timeout 7470A SP1PA1000,1000PDPA1000,6000PUSP0Plotter Applications A PC-Based Graphics System SW3 MacPlot Configuration Screen Setting the Internal DIP Shorting Jumper for RS-422 SW3 Printer Applications Serial and Ieee Input Buffers Peripheral OperationPeripheral-Mode Operation Ieee Data Transfers Controlled BUS Data Transfers Serial-Poll Status-Byte Register DIO8 Ieee Input Buffer not EmptyRsv Not Defined-AlwaysSerial Input Buffer not Empty Ieee Input Buffer FullUse of Serial and Bus Terminators Ieee 488 Bus ImplementationUntalk UNT SW3 View for Ieee Address Selection General Structure Ieee 488 PrimerHistory RS-232↔IEEE 488 Interface Converter Send It to My Address DMMBus Management Lines Handshake Lines Data Valid DAVMultiline Commands Data LinesTalk Address Group TAG More on Service Requests Serial Poll Theory of Operation Address Device Part Number FunctionBoard Layout Component Layout of the Interface Converter’s MotherboardRED BLK Appendix A. Sample Dumb-Terminal Program CLSMultiline Messages SOHHow To Read the Chart Ascii CharacterIndex DIO1 DIO2 DIO3Index SW1 Copyright 1998. Black Box Corporation. All rights reserved