National Instruments 320030-01 Serial Polls, Parallel Polls

Chapter 5 Programming Considerations

© National Instruments Corporation 5-23 GPIB-1014 User Manual

Serial Polls

Conducting a Serial Poll

The TLC, as CIC, can serial poll other devices as described in the IEEE 488 specification. From

the programming point of view, the TLC must first become Active Controller to send the

addressing and enabling commands to the device being polled, make itself a GPIB Listener by

issuing the Listen auxiliary command, and then go to standby with the Go To Standby auxiliary

command to read the status byte.

Responding to a Serial Poll

The CIC can conduct Serial Polls to determine which device is asserting the GPIB SRQ signal to

request service.

Before requesting the service, the recommended practice is to wait until the PEND bit in the

SPSR is zero, indicating that the TLC is not presently in the middle of a Serial Poll (SPAS=0). If

PEND=0, write the desired Status Byte (STB) into the SPMR with the rsv bit set. At that time,

PEND sets and remains set until the Serial Poll completes.

Once rsv is set, the TLC waits until any current Serial Poll is complete before asserting the GPIB

SRQ signal. In response to that signal, the CIC starts the poll addressing the TLC to talk. When

the CIC unasserts ATN, the TLC unasserts SRQ and transfers the STB message onto the GPIB

data bus with DIO7 (the RQS signal) asserted.

While the Serial Poll is in progress (SPAS=1), the CIC normally reads the STB only once;

however, it can read STB any number of times. RQS, rsv, and PEND are cleared when the CIC

asserts ATN to terminate the poll.

The GPIB EOI line is asserted along with the status byte (that is, the END message is sent)

during the Serial Poll if bit B1 of the AUXRB is set.

Parallel Polls

Parallel Polls are used by the GPIB Active Controller to check the status of several devices

simultaneously. The meaning of the status returned by the devices being polled is

device-dependent. Two general ways in which Parallel Polls are useful are as follows:

• When the GPIB Controller sees SRQ asserted in a system with several devices, it can quickly

determine which one needs to be serial polled, usually using only one Parallel Poll.

• In systems in which the Controller response time requirement to service a device is low and

the number of devices is small, Parallel Polls can replace Serial Polls entirely, provided that

the Controller polls frequently.

Contents

Main Page Limited Warranty Copyright Trademarks Page FCC/DOC Radio Frequency Interference Compliance Federal Communications Commission Canadian Department of Communications Instructions to Users Contents Chapter 5 Programming Considerations Chapter 6 Theory of Operation Page Appendix F Mnemonics Key Appendix G Customer Communication Glossary Index Figures Tables About This Manual Organization of This Manual Conventions Used in This Manual Related Documentation Customer Communication Chapter 1 Introduction Page What Your Kit Should Contain Optional Equipment Unpacking Chapter 2 General Description Electrical Characteristics VMEbus Characteristics VMEbus Slave-Addressing VMEbus Slave-Data Table 2-3. 68450 Internal DMA Registers Ad (continues) VMEbus Master-Direct Memory Access Interrupter Data Transfer Bus (DTB) Requester Diagnostic Aids Data Transfer Features Programmed I/O Transfers GPIB-1014 Functional Description Chapter 2 General Description Figure 2-1. GPIB-1014 with a VMEbus Computer National Instruments Corporation 2-9 GPIB-1014 User Manual General Description Chapter 2 Figure 2-2. GPIB-1014 in a Multiprocessor Application GPIB-1014 User Manual 2-10 National Instruments Corporation Chapter 2 General Description National Instruments Corporation 2-11 GPIB-1014 User Manual Figure 2-3 is a block diagram of the GPIB-1014. Figure 2-3. GPIB-1014 Block Diagram Page Page Page Page Page Page Access Mode Base Address Page DMA Address Modifier Code Output Page Other Configuration Parameters Installation Verification of System Compatibility Configuration and Installation Chapter 3 GPIB-1014 User Manual 3-8 National Instruments Corporation Table 3-3. GPIB-1014 Pin Assignment on VMEbus Connector P1 Pin No. Signal Used Signal Not Used Pin No. Signal Used Signal Not Used Chapter 3 Configuration and Installation National Instruments Corporation 3-9 GPIB-1014 User Manual Table 3-4. GPIB-1014 Pin Assignment on VMEbus Connector P2 Signal Signal Signal Signal Pin No. Used Not Used Notes Pin No. Used Not Used Notes Notes Cabling Verification Testing Chapter 4 Register Bit Descriptions Register Map Register Sizes Register Description Page Interface Registers Figure 4-1. Interface Registers Figure 4-2. Writing to the Hidden Registers Data In Register (DIR) Command/Data Out Register (CDOR) Interrupt Status Register 1 (ISR1) Interrupt Mask Register 1 (IMR1) Page Page Page Page Page Interrupt Status Register 2 (ISR2) Interrupt Mask Register 2 (IMR2) Page Page Page Page Serial Poll Status Register (SPSR) Serial Poll Mode Register (SPMR) Address Status Register (ADSR) Page Address Mode Register (ADMR) Page Page Command Pass Through Register (CPTR) Page Auxiliary Mode Register (AUXMR) Page Page Page Page Page Hidden Registers Page Page Page Page Page Page Page Page Address Register 0 (ADR0) Address Register (ADR) Address Register 1 (ADR1) End of String Register (EOSR) DMA Registers Chapter 4 Register Descriptions Figure 4-3. DMA Register Memory Map National Instruments Corporation 4-47 GPIB-1014 User Manual Reprinted from the Motorola MC68440 Advance Information manual. Address Registers Transfer Count Registers Function Code Registers Device Control Register Page Operation Control Register Page Sequence Control Register Channel Control Register Page Channel Status Register Page Channel Error Register Channel Priority Register Interrupt Vector Registers General Control Register Configuration Registers Page Page Page Chapter 5 Programming Considerations Initialization Page The GPIB-1014 as GPIB Controller Becoming Controller-In-Charge (CIC) and Active Controller Sending Remote Multiline Messages (Commands) Going from Active to Standby Controller Going from Standby to Active Controller Going from Active to Idle Controller The GPIB-1014 as GPIB Talker and Listener Programmed Implementation of Talker and Listener Addressed Implementation of the Talker and Listener Page Sending/Receiving Messages Using Direct Memory Access Page Page Page Page Page Page Page Page Page Page Page Using Programmed I/O Interrupts Page Serial Polls Conducting a Serial Poll Responding to a Serial Poll Parallel Polls Conducting a Parallel Poll Responding to a Parallel Poll Chapter 6 Theory of Operation VMEbus Interface Data Lines Control Signals Address Control Equations of Transceivers Address Decoding Clock and Reset Circuitry Configuration Registers Configuration Register 1 Page Configuration Register 2 Timing State Machine Slave Cycles DMA Cycles DMA Gating and Control Interrupter DTB Requester and Controller Page Page GPIB Synchronization and Interrupt Control Page Page 68450 DMAC DMAC Channel Operation Page Page Page Page Page Page Page Page Page GPIB Interface Test and Troubleshooting DMA Stand-Alone Testing GPIB Interface Testing Page Chapter 7 Diagnostic and Troubleshooting Test Procedures Interpreting Test Procedures GPIB-1014 Hardware Installation Tests Page Page Page Page Page Page Page Appendix A Hardware Specifications Page Page Appendix C Sample Programs ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Multiline Interface Messages Hex Oct Dec ASCII Msg Hex Oct Dec ASCII Msg Message Definitions Multiline Interface Messages Hex Oct Dec ASCII Msg Hex Oct Dec ASCII Msg Appendix E Operation of the GPIB Types of Messages Talkers, Listeners, and Controllers The Controller-In-Charge and System Controller GPIB Signals and Lines Data Lines Handshake Lines Interface Management Lines Operation of the GPIB Appendix E GPIB-1014 User Manual E-4 National Instruments Corporation Physical and Electrical Characteristics Figure E-1. The GPIB Connector and Signal Assignments Page Configuration Requirements Related Documents Appendix F Mnemonics Key A B Page C D E F G H I L M N O P R S T Page Appendix G Customer Communication Technical Support Form ____________________________________________________ GPIB-1014 Hardware and Software Configuration Form National Instruments Products Other Products Page Documentation Comment Form Glossary ___________________________________________________ Index Numbers A B C D Page Page Page E F G H I Page J L M N O P Page R S Page T Page Page U V W