IBQ01 BITBUS CONTROLLER Hardware Installation Manual P/N : EK-IBQ01-IN Automatic contents Preface OVERVIEW This manual provides the information to allow the user to install and test the IBQ01 BITBUS Controller. It is written to support an electronic specialist familiar with installing Q-bus options. The manual contains four chapters. Chapter 1 contains a physical description of the IBQ01 including specifications and configurations. Chapter 2 contains the procedures and actions required to install the IBQ01, cabling, interconnect panel and post-installation checkout. Chapter 3 contains a summary of the diagnostic software used to test the IBQ01. Chapter 4 contains a summary of the requirements for installing BITBUS cables and BITBUS devices. RELATED DOCUMENTS In this manual you will find it helpful to refer to the following related manuals. They can help you use and understand the IBQ01 BITBUS Controller. IBQ01 BITBUS Controller Software Installation Manual AA-JQ52A-TN IBQ01 BITBUS Controller User's Guide EK-IBQ01-IN IBQ01 BITBUS Controller Technical Manual EK-IBQ01-TM Distributed Control Modules Handbook Intel's 230973-001 MicroVAX 630 CPU Module Users Guide EK-KA630-UG MicroVAX II 630QY, 630QZ Owners Manual AZ-FE05A-TN MicroVAX II 630QY, 630QZ Technical Manual AZ-FE06A-TN VAX/VMS System Services Reference Manual AA-Z501B-TE IEEE Specification 1118 CONVENTIONS This section describes the special symbols used in this manual. ... Horizontal or vertical ellipses in text means that the information not directly related to the description has been omitted. COMMAND The verb portion of all commands are shown in upper case. NOTES, CAUTIONS, AND WARNINGS Notes, cautions, and warnings used in this manual are defined as follows: NOTE The information is important to the understanding of the process being described. CAUTION The information describes a process that can damage the equipment or software. WARNING The information describes a process that can harm the user. Corrections and suggestions for improving this publication are welcomed. FCC USER STATEMENT NOTICE This equipment generates, uses, and may emit radio frequency energy. The equipment has been tested and found to comply with the limits for a Class A computing device pursuant to Subpart J of Part 15 of FCC rules, which are designed to provide reasonable protection against such radio frequency interference. Operation of this equipment in a residential area may cause interference in which case the user at his own expense will be required to take whatever measures may be required to correct the interference. NOTE All data interconnect cables should be shielded. Refer to Chapter 4 for details on shielding requirement. If you replace or add any cables, they should have equal or greater shielding than those provided by Digital Equipment Corporation. CHAPTER 1 INTRODUCTION 1.1 OVERVIEW This chapter contains an overview of the IBQ01 BITBUS Controller. It includes a brief description of hardware, the IBQ01, and its specifications. 1.2 DESCRIPTION The BITBUS Control System is the hardware, software, and firmware that provides an interface between intelligent devices using BITBUS and application software running on a MicroVAX ll. The IBQ01 hardware consists of a quadboard called the BITBUS controller, a connector panel, a cable, and firmware. The firmware controls the flow of data to and from the BITBUS. It also performs power up diagnostics, initialization, and maintenance of the BITBUS network. The QZEEI software is the interface between the user generated program and the IBQ01 hardware and includes the IBQ01 Software Driver, and the configuration utility. 1.3 OPTIONS The options available with the IBQ01 BITBUS Controller are: Basic Equipment IBQ01-AA BITBUS to Q-bus for BA23/BA123 (requires cable option) Contains M3125 quadboard (with BA23 handle) Hardware Installation Manual EK-IBQ01-IN-001 User's Guide EK-IBQ01-UG-001 IBQ01-SA BITBUS to Q-bus for BA213 (cable included) Contains M3125 quadboard (with BA213 handle) Hardware Installation Manual EK-IBQ01-IN-001 User's Guide EK-IBQ01-UG-001 Cables CK-IBQ01-AA Cable Kit for BA123 (21 inch) CK-IBQ01-AB Cable Kit for BA23 (12 inch) CK-IBQ01-AF Cable Kit for H9642-JA/JB expansion cabinet (36 inch) Software Binary Option (Single use license QZEE1-UZ required) QZZE1-H3 Binaries and Documentation IBQ01 Driver BITBUS Control Service (BCS) 8044 Cross-assembler QZZE1-H5 TK50 Binaries and Documentation IBQ01 Driver BITBUS Control Service 8044 Cross-assembler Software License Option QZZE1-UZ Single use license QZZE1-HZ Right to copy license MicroVAX Diagnostic Manager #nnn Software Documentation Option QLZE1-GZ Documentation only 1.4 RELATED DOCUMENTS The related documents are listed in the preface. 1.5 SPECIFICATIONS 1.5.1 Performance Specifications Of The BITBUS Port Synchronous Mode: Speed 2.4 Mbits/second Maximum segment distance 30 meters (99 ft) Number of nodes per segment 28 Number of segments 1 Total allowable distance 30 meters (99 ft) Total number of addresses 28 Self Clocked Mode: Speed - high 375 kbits/second Maximum segment distance 300 meters (990 ft) Number of nodes per segment 28 Number of segments 3 Total allowable distance 900 meters (2570 ft) Total number of addresses 84 Speed - low 62.5 kbits/second Maximum segment distance 1200 meters (3960 ft) Number of nodes per segment 26 Number of segments 11 Total allowable distance 13,200 meters (43,560 ft) Total number of addresses 250 A segment is a length of wire with BITBUS nodes attached. See Chapter 4 for a detailed definition. 1.5.2 General Specifications 1.5.2.1 Environment and Electrical Operating Temperature 150 to 600 C 590 to 1400 F Relative Humidity 20% to 80% (non-condensing) Altitude 2.4 km 8000 ft Power Requirements 5.0 amperes maximum @ 5 Vdc 0.3 amperes maximum @ 12 Vdc Heat Dissipation 90 BTU per hour Bus Loading 4.6 ac Q22 bus load 1 dc Q22 bus load 1.5.2.2 IBQ01-AA Dimensions Height 26.54 cm 10.45 inches Length 21.41 cm 8.43 inches Width (non conductive) 0.95 cm 0.37 inches (conductive) 0.87 cm 0.34 inches 1.5.2.3 IBQ01-SA Dimensions Height 26.67 cm 10.5 inches Length 30.8 cm 12.125 inches Width (non conductive) 2.54 cm 1 inch (conductive) 1.5.2.4 RS485 Specifications A BITBUS port complies with RS485 specifications. See Chapter 4 Section 4.4 for an RS485 specification summary. 1.5.2.5 Connector Panel For the BA23 or the BA123 installations, the connector panel contains a 9 pin 'D' subminiature plug. Select the cable option to fit your configuration (I/O panel insert size B). For the BA213/BA214 the 9 pin 'D' subminiature plug is built into the handle and a 6 inch quadboard to connector cable is supplied with the board. 1.6 CONTROLS AND INDICATORS The BITBUS controller has four LED indicators for use by maintenance personnel and three switch packs (address, vector, and BITBUS speed) which are set at installation. 1.7 OVERALL FUNCTIONAL DESCRIPTION The IBQ01 performs as a message server between the MicroVAX II and and the BITBUS and as a back-end controller for the BITBUS. Figure 1-1 is an overall functional block diagram of the IBQ01 BITBUS Controller. The board contains: oo A supervisory microprocessor (control processor) oo A BITBUS master controller microprocessor oo 512 kbytes of dual ported DRAM memory oo Q-bus interface with DMA controller, programmed message port, and control and status register (CSR) oo Serial BITBUS industrial communications port The control processor consists of a 16 bit microprocessor and its supporting devices which: oo Establishes communications with the MicroVAX II oo Controls and monitors the BITBUS oo Accesses remote node data oo Sends remote node data through DMA to the MicroVAX II oo Monitors the operation of the IBQ01 BITBUS Controller The BITBUS master controller is an 8-bit microprocessor which supports the BITBUS communications protocol and controls the operations of the BITBUS. The Q-bus interface includes: oo A command and status register (CSR) for status and control handshake with the MicroVAX II. oo A programmed I/O message port (PMP) that acts like a bi-directional, word-wide FIFO for command message strings. oo A DMA interface for control mode and block mode data transfers. Figure 1-1 IBQ01 Block Diagram The user is responsible for the BITBUS control programs and the configuration files. CHAPTER 2 INSTALLATION OF THE IBQ01 BITBUS CONTROLLER 2.1 OVERVIEW This chapter contains procedures for site preparation, pre-installation considerations, and installation for the IBQ01 BITBUS Controller. Also included are checkout procedures to ensure that the installed IBQ01 is operational. 2.2 UNPACKING AND INSTALLATION Component parts of the IBQ01 BITBUS Controller are shipped in a single container and are packed in accordance with commercial packing practices. Remove all packing materials and check the equipment against the shipping list. Inspect the unit for damage as you remove it from the carton checking for dents scratches and loose parts. Check the carton for small parts that may have fallen off. Damage to the unit and shortages in package inventory should be reported to the shipper at once. 2.3 PREINSTALLATION CONSIDERATIONS This section describes the major considerations concerning mounting requirements, device placement, switch pack selections including device address and vector assignments, and Q-bus bandwidth restrictions. 2.3.1 Physical Requirements The IBQ01 BITBUS Controller requires one quad slot in the CPU's Q-bus backplane. 2.3.2 Q-bus Device Placement Placement of the IBQ01 BITBUS Controller is dependent upon the other boards in the MicroVAX II (see the MicroVAX Technical Manual). The IBQ01 has an interrupt priority level 4. To get a higher level servicing for this board, place it nearer to the KA630 CPU board (after the memory). A typical placement in a BA23 cabinet is shown in Figure 2-1. Figure 2-1 Typical BA23 Placement For IBQ01 2.3.3 Q-bus Device Address and Vector Assignments The IBQ01 BITBUS Controller device address is switch selectable between 760000 and 777777, which is in the fixed Q-bus I/O address space. The vector address is selected from the floating vector space between 300 and 774 and has a ranking of 78. The vector address is switch selectable. Rank Size Modulus (octal) CSR 50 2* 10 Vector 78 2 4 * If configuring multiple IBQ01s, use word size=4 since this board cannot be configured on odd double-word boundaries. The default values when shipped from the factory are: CSR = 760770 Vector = 300 2.3.4 Switch Pack Selections There are three switch packs on the IBQ01 module. See Figure 2-2 for switch pack location and setting information. Figure 2-2 IBQ01 Switch Pack Location 2.4 CONNECTOR PANEL The presence of a connector panel is dependent upon the cabinet type. For the BA23 and the BA123 cabinets, the connector panel is mounted on the I/O distribution panel. For the BA213 and BA214 cabinets the connector is integral to the handle on the IBQ01 module. 2.5 CABLING With the BA213 and BA214 installations the cabling from the module to the connector panel is integral to the board. The cable supplied with the kit connects from the module to the connector on the module handle. With the BA23, BA123, and H9642 extender cabinet you must obtain the matching cable kit: oo BA23 - requires 12 inch cable oo BA123 - requires 21 inch cable oo H9642 - requires 36 inch cable 2.6 INSTALLATION To install the IBQ01 module perform the following procedure. 1. Review the shipping list and verify that all items have been received. 2. Verify that you have the proper cable length for your cabinet (for non BA213/BA214 installations). 3. Verify that the switch packs and grant jumpers are properly configured for your system configuration (see Figure 2-2). CAUTION For BA23 frames, the C and D rows of slots 1, 2, and 3 provide an intercon nection between the three slots. This interconnection is referred to as the CD interconnect. To install the IBQ01 in one of the first three slots, you must remove the jumpers W1 and W2 from the IBQ01. To install the IBQ01 in one of the first four slots of BA123 frames, you must remove the jumpers W1 and W2 from the IBQ01. To install the IBQ01 in any of the slots of the BA213 or BA214 frames, you must remove the jumpers W1 and W2 from the IBQ01 (see Figure 2-2). Dual height modules in either the AB or CD rows of slots 3 through 8 require another dual height module or an M9047 grant card in the other two rows of the slot. 4. Notify all users on the system and then turn the system power off. 5. Install the IBQ01 in the selected slot in Q-bus backplane. Your selection should be based on the desired interrupt priority. 6. Install the connector panel and attached cable for non BA213/BA214 installations to the I/O distribution panel. With the BA23 I0 distribution panel you can install up to three IBQ01 connector panels. 7. Install the customer supplied external BITBUS cable (see Chapter 4 for a summary of BITBUS cable requirements). To meet FCC requirements for a class A product, the customer supplied external BITBUS cable must be shielded. A. For BA213 or BA214 installations (with door), open the door and route the cable up through the rubberized material in the cableway and connect the BITBUS cable to the connector on the handle of the IBQ01 BITBUS Controller. B. For non BA213/BA214 installations, connect the customer supplied external BITBUS cable to the IBQ01 Connector Panel. 8. Make sure the IBQ01 module and the cables are properly seated in their connectors. The IBQ01 is now installed. Install the software and run the diagnostic tests in the BITBUS Control Service (BCS) software package. 2.7 FIELD CHECKOUT AND ACCEPTANCE PROCEDURE Turn the system power on and observe the four LEDs on the IBQ01. The IBQ01 will perform a series of self tests during power up. When it successfully completes the power-up self tests the green LED will light and the adjacent red LED will extinguish. Any other condition of these two LEDs is unsatisfactory and signals a hardware defect. The other two red LEDs sample activity on the BITBUS receive and transmit lines. One indicates that data is being transmitted and the other indicates that data is being received. These two red LEDs are not involved with the self-test diagnostics - they show bi-lateral communications. 2.7.1 Built-in Diagnostics The built-in diagnostics are invoked upon power-up, system reset or boot. These diagnostics check the functional integrity of the board including: oo Supervisory microprocessor oo BITBUS master controller microprocessor oo Dual ported memory oo Other onboard functions No data is transmitted over the BITBUS wire during these tests, nor is any Q-bus activity initiated. 2.7.2 Diagnostic Checks When you have completed running the built-in diagnostics, run the IBQ01 MDM for three error free passes. You must run the diagnostic tests in MDM to fully verify all functional components. CHAPTER 3 INSTALLATION CHECKOUT AND VERIFICATION 3.1 OVERVIEW This chapter describes how to checkout and verify the operation of the IBQ01 BITBUS Controller after installation. 3.2 DIAGNOSTIC TESTING To fully test the IBQ01 BITBUS Controller, use the built-in diagnostic test and the MDM diagnostic program. The MDM program is available from Digital's Software Distribution Center (SDC). 3.3 DIAGNOSTIC OVERVIEW The MDM diagnostic, which runs under the MDM system, isolates IBQ01 failures at the Field Replaceable Unit (FRU) level (the controller module or the cable kit). MDM has two nodes of operation: oo Verify mode - contains the verify functional tests and the service exerciser. oo Service mode - contains the service functional tests and the service exerciser. This mode is designed to run with a slave node (node address 250) BITBUS node connected to the BITBUS. The test tree (see Figure 3-1) shows the normal sequence of operation using the MDM with emphasis on the IBQ01 branch. The BCS Diagnostic verifies that the IBQ01 performs checks the functional operation of the IBQ01 module. Figure 3-1 MDM Test Tree Table 3-1 shows the test coverage of each diagnostic test. Table 3-1 Diagnostic Error Messages The error messages indicate the failing test and the failure cause. __________________________________________________________________ Error No Description __________________________________________________________________ 01 Unable to write to CSR register 03 Unable to read from CSR register 03 CSR register gives erroneous response 11 Could not set CSR auto QBUS interrupt bit 12 Could not clear CSR auto QBUS interrupt bit 13 Could not auto interrupt the QBUS 14 Device auto interrupted the QBUS more than once 15 Device interrupts at incorrect level 16 Device interrupts at incorrect level 21 Device will not release PMP receive port 22 Unable to write to PMP transmit port 23 No interrupt response to FORCED ERROR command 23 Device will not release PMP receive port 25 Device will not release PMP transmit port 26 Unable to read from PMP port 27 Incorrect response to FORCED ERROR command 31 Device failed on-board CPU diagnostic 32 Device failed on-board RAM diagnostic 33 Device failed on-board CLOCK diagnostic 34 Device failed on-board TIMER diagnostic 35 Device failed on-board 8044 diagnostic 41 Incorrect response to DOWNLOAD MEMORY RAC command 42 Incorrect response to UPLOAD MEMORY RAC command 43 DMA transfer to QBUS wrote outside memory bounds 44 DMA upload data does not match DMA download data 45 DMA transfer to QBUS wrote outside memory bounds 51 Incorrect controller response to ONLINE command Table 3-1 Diagnostic Error Messages (Cont) __________________________________________________________________ Error No Description __________________________________________________________________ 52 Incorrect controller response to GET FUNCTION ID command 53 Incorrect remote node response to GET FUNCTION ID command 54 Incorrect remote node RAC TASK ID received 101 No response to BUSSRCH command 102 No response to ONLINE command CHAPTER 4 INSTALLING BITBUS DEVICES 4.1 OVERVIEW This chapter contains a summary of the requirements for installing a BITBUS network. For more information on installing BITBUS networks, see Intel's Distributed Control Modules Databook 230972-002 and the user's guides for the specific BITBUS compatible remote devices in your BITBUS network. 4.2 DEFINITION OF TERMS A typical BITBUS system contains dedicated intelligent controllers and process I/O points with a host computer as supervisor. The BITBUS interconnect concept allows multidrop, expandable, distributed processing capabilities through a low cost communications vehicle. BITBUS uses a master-node slave-node relationship to insure that only one member communicates on the line at a time and guarantees access to all members. The IBQ01 has a BITBUS master node to supervise and control the communications functions of this interconnect system. NODE - A node is a member of a BITBUS interconnect system. Each node requires RS485 transceivers and an SDLC controller to support the data-link-protocol requirements defined in the BITBUS specifications. There are two types of nodes: oo Master node - This node initiates all communications interactions. The IBQ01 acts as a master node and can support up to 250 slave nodes. oo Slave node - These nodes respond to commands or requests from the master node. A slave node cannot initiate a transaction without a master node. SEGMENT - A segment is a length of wire with BITBUS nodes attached. Any segment can have up to 28 nodes, and depending on speed selection, multiple segments can be attached using repeaters. See Chapter 1 Section 1.5.1 for the relationship of speed to distance and the number of segments. REPEATER - A repeater is an RS485 transceiver pair which rebroadcasts BITBUS messages from one segment of a BITBUS to another. A repeater represents the load of one node but is not intelligent. Repeaters use the RTS/RTS signal pair to determine whether they should transmit or receive. Therefore, repeaters cannot be used in synchronous mode operation. (Synchronous mode requires the signal pair to function as DCLK/DCLK.) The IBQ01 supports repeater functionality in self clocked operation within the guidelines of the BITBUS specification. The number of repeaters allowable in a BITBUS interconnect system is controlled by the speed selected (see Chapter 1, Section 1.5.1). 4.3 MECHANICAL SPECIFICATION The IBQ01 supports the BITBUS interconnect standards for both cable connectors and standard printed circuit board connectors. With the IBQ01-AA, the printed circuit connector is on the board and the CK-IBQ01 cable kits provide an interconnect from the board to the MicroVAX distribution panel, and supply a cable connector to the user. The IBQ01-SA has the cable connector interface built into its handle and does not support the printed circuit interconnect. 4.3.1 Connector Specifications for the dimensional requirements of the printed circuit interconnect are shown in Figure 4-1 and the connector pin assignments are contained in Table 4-1. Figure 4-1 Printed Circuit Interconnect Table 4-1 Connector Pin Assignments The standard cable to printed board connector is a 10 pin latching pin and socket type with strain reliefs. The connector can support either flat cable or discrete wire connections. Use a AMP 74- nnn type connector or its equivalent. The board provides the pins and latching functions. The user should supply the socket type receptacle. Specifications for the dimensional requirements of the cable to cable connector are shown in Figure 4-2. The standard cable to cable connector is a 9 pin D-subminiature type. Versions of this connector are also available for flat cable or discrete wire connection. The IBQ01-SA and the CK IBQ01 provide the 9-pin plug, so the user must supply the mating socket. See Table 4. for connector pin assignments. Figure 4-2 Cable to Cable Connector 4.3.2 Connector Power The IBQ01 provides power and ground for limited node power requirements. Pins 1 and 6 (on the cable connector) provide 10.5 V +- 10% at 330 milliamperes. This supply is thermally current limited at about 1 ampere for short circuit protection (see Figure 4-3). Pins 2 and 7 (on the cable connector) provide a fused connection (see Figure 2-1) to the MicroVAX ground. Pin 5 (also on the cable connector) provides a 100 ohm resistance path to ground and is compatible with the BITBUS specifications. Figure 4-3 Connector Power Connections 4.3.3 Cabling The RS485 component for the BITBUS specification provides differential transceivers and requires twisted pair wire to keep common mode noise to a minimum. For a single segment, running in self clocked mode, only one pair of wires is required for DATA and DATA. If repeaters are used, a second wire pair (RTS and RTS) is required to control the data direction on the repeater transceivers. If the BITBUS is used in synchronous mode (2.4 MHz), then the second wire pair (DCLK and DCLK) is required for clock data. Low cost cables, capable of handling the 28 BITBUS loads (1.125 x RS485 unit loads per BITBUS load) and 60 ohm of termination is all that is required for the twisted wire pairs. For a class A product, FCC requires that this cable be shielded. Shielding may be braided or foil and a connector shield should be used to connect the wire shield to the chassis of the MicroVax. An example of an acceptable RFI/EMI shield is shown in Figure 4-4. Figure 4-4 Connector Shielding Cables chosen should have a characteristic impedance of at least 120 ohms for properly matching terminators. Take care to ensure that the cable chosen will support the bit rate selected over the distance required without attenuating the signals below the specifications. Also, the cable must be chosen with a low enough dc resistance to guarantee sufficient voltage across the termination at the receivers. This parameter, the attenuation, and the magnitude of reflections need to be considered together to determine the worst case noise margin at the receivers. 4.3.4 Termination All BITBUS interconnect cables must be terminated at both ends for proper operation. The IBQ01 is considered a master node and is usually located at one end of the BITBUS cable. Therefore the boards are shipped with 120 ohm termination resistors installed (see Figure 4-5). If your installation has the IBQ01 other than at one of the ends you must remove these resistors (see Figure 2-3). Figure 4-5 BITBUS Signal Pair Lines Termination 4.4 RS485 SPECIFICATION SUMMARY 4.4.1 DC Specifications Standard unit loads for BITBUS is 1.125 RS485 unit loads and is specified in Figure 4-6 over the input voltage range of + 12v to - 7 V Figure 4-6 Standard Unit Data 4.4.2 Transmitter Specification The shaded area in Figure 4-6 represents the acceptable region for I/V characteristics representing one unit load. The transmitter on the IBQ01 meets the requirements of an RS485 generator. It is capable of driving a 60 ohm termination and up to 28 standard unit loads as defined in Figure 4-6. The transmitter is able to withstand the following: oo Outputs shorted together oo Outputs directly connected to a current limited voltage source within the + 12 V to - 7 V range 4.4.3 Receiver Specification The IBQ01 receiver meets the requirements of an RS485 receiver. 4.4.4 AC Specifications The AC specifications for the BITBUS interconnect requires definition of the signal line characteristics, transmitter enable timing, self clocked mode timing, and repeater timing. 4.4.5 Signal Line Characteristics The BITBUS signal lines must maintain a reasonable level of signal integrity to guarantee proper operation. Specifically, there needs to be bounded rise and fall times and reflection guidelines. The BITBUS signal lines shall have rise and fall times between 25 and 100 nanoseconds as shown in Figure 4-7 as measured in a test configuration (see Figure 4-8). Figure 4-7 Rise And Fall Specifications Figure 4-8 Test Configuration for Rise And Fall Time 4.4.6 Reflection Guidelines Transitions on the BITBUS signal lines from 10% to 90% of the final steady state value shall be monotonic and ringing is limited to ±10% around the final steady state value. RS485 provides a significant dc noise margin. In systems where reflections can be unavoidable, these noise margins are used to guarantee operation. When choosing a cable, potential reflections due to lumped capacitive loads, mismatched terminations, or excessively long stubs, should be considered along with the dc losses. In all cases, the voltage at any node shall remain in the +12 V to -7 V common mode range except for pulses of less than 15 microseconds, at less than 1% duty cycle, which shall be bounded to ±25 volts. 4.5 SUMMARY OF INSTALLATION When installing a BITBUS system, use the following guidelines: oo For synchronous operation, the BITBUS cable can be a maximum of 30 meters and no repeaters can be used. The DCLK/DCLK signal wire pair must be supplied in the BITBUS cable. The IBQ01 will transmit messages at 2.4 Mbits/sec but will receive messages ant any speed since the clock is generated from the slave node. See Chapter 2, Section 2.2.4 for speed switch settings. oo For self clocked operation, you can select speeds of 375 kbits/sec or 62.5 kbits/sec (see Chapter 2, Section 2.2.4). At 375 kbits/sec you can use up to three segments (two repeaters) supporting up to 84 nodes. At 62.5 kbits/sec you can use up to 11 segments (10 repeaters) supporting up to 250 nodes. When using repeaters, the RTS/RTS signal wire pair must be supplied in the BITBUS cable. oo The extreme ends of each segment should be terminated with 120 ohm resistors. The 120 ohm resistors are installed on the IBQ01 board (see Figure 2-3). Cabling should be shielded with single-end ground attachment at the MicroVAX. Cable routing should avoid any large EMI/RFI sources (dc motors,...) to reduce common mode noise injection on the wire. oo Remote node addresses may be selected between 1 and 250. The IBQ01 master node does not have an address as a master. If the board is used with other master nodes, the IBQ01 defaults to address 01. 4.6 FAULT DIAGNOSIS If your system does not communicate properly, answer the following questions before calling your Digital service representative. 1. Does the IBQ01 pass its diagnostic tests? If not, call your Digital Representative. 2. Are all of the nodes and the IBQ01 set to the same speed selection? If not, set them to the same speed. 3. Are the cables properly installed, check for shorts and opens? Do you need DCLK or RTS signals? Fix the problem with the cable. 4. Do all of the nodes (devices) on the system have a unique address? Give each node a unique address. 5. Do any of the nodes respond to an ONLINE command? A. If so, the fault is not in the IBQ01 - check your cabling and remote sites. B. If none do, recheck the 1 through 4 above. 6. Is there excessive noise (EMI/RFI) on the system cabling? If so, remove the noise source or reroute the cable. 4.7 LEVELS OF COMPLIANCE In order for the BITBUS interconnect products to meet the minimum level of compliance it must meet the following. 4.7.1 Electrical Interface The electrical interface supports variability in bit rates, load characteristics, and repeater characteristics. Of the supported bit rates, only one speed synchronous 62.5 kbits/sec or 375 kbits/sec is required. The others may optionally be supported. 4.7.2 Data Link Protocol There are no optional features on the data link protocol. 4.7.3 Message Protocol The message protocol supports variability in message length. All implementations shall support the standard 7 byte header and 13 byte data field. 4.7.4 Remote Access And Control (RAC) Support of the remote access and control function is completely optional. To make full use of the IBQ01 functionality the BITBUS devices must be RAC compatible (see the IBQ01 BITBUS Controller User's Guide). 4.7.5 Mechanical The mechanical specification requires connector compliance and cable shielding.