GPIB-BUF User Manual February 1994 Edition Part Number 320125-01 © Copyright 1989, 1994 National Instruments Corporation. All Rights Reserved.
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MicroGPIB Products National Instruments has developed the MicroGPIB product line to offer a series of high performance, low cost IEEE 488 support items that are packaged in small all-metal cases, capable of being rack mounted. Limited Warranty The GPIB-BUF is warranted against defects in materials and workmanship for a period of two years from the date of shipment, as evidenced by receipts or other documentation.
action accrues. National Instruments shall not be liable for any delay in performance due to causes beyond its reasonable control.
FCC/DOC Radio Frequency Interference Compliance This equipment generates and uses radio frequency energy and, if not installed and used in strict accordance with the instructions in this manual, may cause interference to radio and television reception. This equipment has been tested and found to comply with the following two regulatory agencies: Federal Communications Commission This device complies with Part 15 of the Federal Communications Commission (FCC) Rules for a Class A digital device.
There is no guarantee that interference will not occur in a particular installation. However, the chances of interference are much less if the equipment is installed and used according to this instruction manual. If the equipment does cause interference to radio or television reception, which can be determined by turning the equipment on and off, one or more of the following suggestions may reduce or eliminate the problem.
Contents About This Manual .......................................................................... ix Introduction to the GPIB-BUF ................................................... ix Organization of This Manual...................................................... ix Conventions Used in This Manual ............................................. x Related Documentation ..............................................................x Customer Communication .................................................
Contents Appendix A Hardware Specifications ..............................................................A-1 Appendix B Customer Communication .......................................................... B-1 Glossary............................................................................................... G-1 Figures Figure Figure Figure Figure 1-1. 1-2. 1-3. 1-4. The GPIB-BUF ................................................................... 1-1 The GPIB-BUF Front Panel ............................
About This Manual Introduction to the GPIB-BUF The GPIB-BUF is one of National Instruments family of MicroGPIB products. These products are high-performance, low-cost IEEE 488 support items, packaged in small all-metal cases, capable of being rack mounted. Organization of This Manual This manual is organized as follows: • Chapter 1, Description of the GPIB-BUF, contains general information about the National Instruments GPIB-BUF and lists components and accessories.
About This Manual Conventions Used in This Manual The following conventions are used in this manual. italic Italic text denotes emphasis, a cross reference, or an introduction to a key concept. bold italic Bold italic text denotes a note, caution, or warning. bold Bold text denotes the name of light-emitting diode (LED). Abbreviations, acronyms, metric prefixes, mnemonics, symbols, and terms are listed in the Glossary.
Chapter 1 Description of the GPIB-BUF This chapter contains general information about the National Instruments GPIB-BUF and lists components and accessories. Introduction The GPIB-BUF, shown in Figure 1-1, is an IEEE 488 (GPIB) data buffer which increases GPIB performance by isolating a slow GPIB data acceptor from the rest of the GPIB system.
Description of the GPIB-BUF Chapter 1 The GPIB-BUF has two isolated GPIB ports and is placed in-line between a GPIB system and a single, slower GPIB device (usually a printer or plotter). The GPIB-BUF automatically buffers all device-dependent data sent to the slower device. Because the GPIB-BUF can talk or listen on either port at any time, the GPIB-BUF provides fully transparent bi-directional data transfers. The target GPIB device appears to be connected directly to the IEEE 488 bus.
Chapter 1 Description of the GPIB-BUF The GPIB-BUF Front Panel The power switch and six Light Emitting Diodes (LEDs) are mounted on the GPIB-BUF front panel. Figure 1-2 shows the front panel of the GPIB-BUF. NATIONAL INSTRUMENTS GPIB-BUF IEEE-488 BUFFER IEEE-488 POWER READY TALK LISTEN EMPTY FULL Figure 1-2. The GPIB-BUF Front Panel The LEDs show the current status of the GPIB-BUF at all times. The following table describes each LED. Table 1-1.
Description of the GPIB-BUF Chapter 1 The GPIB-BUF Rear Panel Figure 1-3 shows the power cable and the GPIB cables connected to the rear panel of the GPIB-BUF. Figure 1-3. The GPIB-BUF Rear Panel The GPIB Connectors The GPIB-BUF has two GPIB connectors labeled GPIB IN and GPIB OUT. Both GPIB connectors are standard 24-pin shielded AMP CHAMP female connectors with metric screwlock hardware. As you face the rear panel, the GPIB IN connector is the right-most GPIB connector.
Chapter 1 Description of the GPIB-BUF The port labeled GPIB IN is intended to be connected to a GPIB system that includes one or more GPIB devices which send data to the GPIB target device. All data received via the GPIB IN port is transferred into the Random Access Memory (RAM) buffer of the GPIB-BUF using the onboard Direct Memory Access (DMA) controller. The port labeled GPIB OUT should be connected to the GPIB target device.
Chapter 2 Installation and Operation This chapter describes the procedures for installing and operating the GPIB-BUF. Figure 2-1 shows an example of a GPIB-BUF connected to a GPIB system. This example shows a GPIB-BUF placed in a GPIB system with a GPIB Talker/Controller, such as an IBM-PC with a National Instruments GPIB-PCII Controller board installed, and a slow GPIB data acceptor, such as an HP 7475A Color Plotter.
Installation and Operation Chapter 2 Installation Install the GPIB-BUF according to the following procedure. 1. Inspect the GPIB-BUF. 2. Verify the voltage requirement. 3. Configure the operating parameters. 4. Connect the cables. 5. Power on the unit. These steps are described in more detail in the following subsections. Step 1. Inspect the GPIB-BUF Before you install the GPIB-BUF, inspect the shipping container and its contents for damage.
Chapter 2 Installation and Operation Step 3. Configure the Operating Parameters The GPIB-BUF is shipped from the factory configured to operate at a GPIB primary address of 5 with the SRQ-on-empty function disabled and device clear recognition and pass through enabled. The address specified on the configuration switches should match the GPIB address of your target device.
Installation and Operation Chapter 2 Set Configuration Switches Use the DIP switch at location U38 on the printed circuit board to configure the GPIB primary address and operating modes of the GPIB-BUF. The DIP switch has eight configuration switches. Figure 2-2 shows the factory default setting. Key = depressed side of switch handle O N 1 2 3 4 5 6 7 8 O F F Figure 2-2.
Chapter 2 Installation and Operation Table 2-2.
Installation and Operation Chapter 2 Table 2-2.
Chapter 2 Installation and Operation Step 5. Power on the Unit Power on your target device then power on your GPIB-BUF by using the front panel rocker switch. The POWER LED should light immediately and the READY indicator should blink while the unit executes its power-on self-test. The READY indicator should stop blinking and remain on when the GPIB-BUF has passed its power-on self-test indicating the unit is ready for operation.
Chapter 3 Technical Information This chapter contains a more detailed description of the operation of the GPIB-BUF. The timing characteristics of the parallel port are provided in this chapter. The GPIB-BUF is actually a powerful 8-bit microcomputer tailored for use as an IEEE 488 data buffer. The operating system of the unit is contained in Read-Only Memory (ROM) and can address up to 1 MB of dynamic Random Access Memory (RAM).
Technical Information Chapter 3 If the SRQ-on-empty feature is enabled, the GPIB-BUF asserts the Service Request (SRQ*) signal on the GPIB IN port. The SRQ condition can be used to signal the GPIB Controller that the GPIB-BUF is powered on and ready to accept data. Addressing The five GPIB address switches (U38, switches 4 through 8) become the GPIB primary address to which the GPIB IN port responds.
Chapter 3 Technical Information DMA Controller transfers the data directly to the internal data buffer without processor intervention. Thus, GPIB transfer rates as high as 900 kbytes/s are possible. The GPIB-BUF turns off the EMPTY indicator as soon as it starts receiving data from the host. The buffered data is then sent to the target device connected to the GPIB OUT port at the maximum acceptance rate of the target device.
Technical Information Chapter 3 When receiving data while addressed as a GPIB Listener, the GPIB-BUF buffers the state of the EOI* signal line along with the data byte it corresponds to using an additional on-board RAM module. Therefore, the GPIB-BUF is able to maintain the EOI status with each byte received even when the DMA Controller is transferring data directly to memory.
Chapter 3 Technical Information Polling the GPIB-BUF The GPIB-BUF can return status information to the GPIB Controller through the serial poll response byte as shown in Figure 3-1. This byte contains two bits of information that reflect the current condition of the GPIB-BUF data buffer and whether the GPIB-BUF is asserting the SRQ* signal on the GPIB IN port.
Technical Information Chapter 3 The GPIB-BUF SRQ-on-empty feature and serial poll status byte are useful for several reasons. • A remote Controller is able to tell when a data transfer to a plotter or printer is completely finished. • A ready indicator is provided to a remote GPIB Controller signaling that the GPIB-BUF has been powered on, has successfully completed its self-test, and is ready to accept data.
Chapter 3 Technical Information Internally, the local Individual Status (ist) bit of the GPIB-BUF is reset to 0 when the internal data buffer is empty of data. It is set to 1 when the internal data buffer is not empty. Therefore, after the GPIB Controller configures the GPIB-BUF with a Parallel Poll Enable (PPE) message from 60 to 67 hex, the GPIB-BUF, during a parallel poll, drives the data line (which the Controller has specified) active when the internal data buffer is empty.
Technical Information Chapter 3 Special Note About Timeouts If your current GPIB system relies on a timeout method to ensure a nonfunctioning GPIB device does not hang the bus indefinitely, then it may be necessary to adjust or disable the time limit to ensure that the target device has enough time to respond to any requests for information. For example, suppose that your current code sends a file to a plotter and then prompts the plotter for its current status.
Chapter 3 Technical Information internal data buffer. This mode can be used to prematurely abort a lengthy plot or print. Neither Group Execute Trigger (GET), Go To Local (GTL), nor Local Lockout (LLO) have any effect on the GPIB-BUF. The GPIB IN port on the GPIB-BUF can only act as a GPIB Talker or Listener. It should not be passed control. If it is, the GPIB circuitry in the GPIB-BUF will accept control and immediately assert ATN*.
Chapter 1 Description of the GPIB-232CV Appendix A Hardware Specifications This appendix lists the electrical, environmental, and physical specifications of the GPIB-BUF. Table A-1. Electrical Characteristics Characteristic Specification Power Supply Unit Wall mount type, 115 VAC or 230 VAC, 50/60 Hz input, 9 VDC @ 1A max output Voltage 9 VDC regulated Current 700 mA typical; 1.0 A max Table A-2.
Hardware Specifications Appendix A Table A-3. Physical Characteristics Characteristic Specification Case Size 1.6 in. by 5.7 in. by 8.4 in. (40.6 mm by 144.8 mm by 213.4 mm) Case Material All metal enclosure Rack Mounting Single or dual kits available Weight 28 oz. (796 gm) without power supply unit GPIB-BUF User Manual A-2 © National Instruments Corp.
Appendix B Customer Communication For your convenience, this appendix contains forms to help you gather the information necessary to help us solve technical problems you might have as well as a form you can use to comment on the product documentation. Filling out a copy of the Technical Support Form before contacting National Instruments helps us help you better and faster. National Instruments provides comprehensive technical assistance around the world. In the U.S.
Technical Support Form Technical support is available at any time by fax. Include the information from your configuration form. Use additional pages if necessary.
The problem is List any error messages The following steps will reproduce the problem
Hardware Configuration Form Record the settings and revisions of your hardware on the line to the right of each item. Update this form each time you revise your hardware configuration, and use this form as a reference for your current configuration.
Documentation Comment Form National Instruments encourages you to comment on the documentation supplied with our products. This information helps us provide quality products to meet your needs. Title: GPIB-BUF User Manual Edition Date: February 1994 Part Number: 320125-01 Please comment on the completeness, clarity, and organization of the manual.
If you find errors in the manual, please record the page numbers and describe the errors. Thank you for your help.
Glossary Prefix Meaning Value µm- micro 10-6 milli- 10-3 k- kilo- 103 M- mega- 106 ° % degrees percent A AC ANSI C EMI FCC GPIB Hz IEEE in.
