DM5854HR/DM6854HR Isolated digital I/O
Contents
1. Control Byte 88h Isolated digital input programming The optoisolated digital inputs may be addressed directly by reading the digital input register in address BA 0 The DM6854HR features more advanced modes of input pattern or bit change recognition to reduce software overhead This is possible with the hardware interrupt generated by the onboard comparison logic The following two subsections will illustrate how to program the different modes of the isolated digital input port 1 Software controlled direct read in_data inp BA Loads data from inputs into variable in_data 2 Interrupt driven read upon change in bits mask 0x55 Odd bits are of interest state 0x01 Any of bits 3 5 7 goes high or bit 1 goes low outp BA l mask Program mask register outp BA 2 state Program bit inversion register outp BA 3 0x01 Enable interrupts outp BA 0x00 Clear hardware interrupt if state had already occurred Now if any of bits 3 5 7 goes high or bit 1 goes low it will cause a hardware interrupt In your ISR you will read the input data with in data inp BA DM5854HR DM6854HR Page 34 c RTD Finland Oy 1996 2001 Isolated digital output programming The four bit digital output port can directly be programmed from software by writing output data to the high bits 4 8 of I O port address BA 3 Care must be taken to ensure the lower four bits remain unchanged since they hold the configuration data of yo2. External I O connections Figure 2 3 shows the interface connector layout of the DM6854HR This connector is located toward the top of the board Refer to this diagram when making isolated signal output connections Figure 2 4 shows the standard I O connector pinout Figure 2 3a shows the screw terminal discrete wire connector pinout and figure 2 3b shows the pinout of the same connector using a header connector Pin 1 is to the left side of the connector ALL SIGNALS ARE ISOLATED 1 IN1 2 IN1 3 IN2 4 IN2 Ds IN3 6 IN3 T IN4 8 IN4 9 IN5 10 INS5 11 IN6 12 IN6 13 IN7 14 IN7 15 IN8 16 IN8 17 OUT1_COLLECTOR 18 OUT1_EMITTER 19 OUT2_COLLECTOR 20 OUT2_EMITTER 21 OUT3_COLLECTOR 22 OUT3_EMITTER 23 OUT4_COLLECTOR 24 OUT4_EMITTER Fig 2 3a Isolated Input Output interface using screw terminal block connector DM5854HR DM6854HR Page 18 c RTD Finland Oy 1996 2001 1 2 3 4 5 6 7 8 9 10 11 12 13 34 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 3 1 32 33 34 35 36 37 38 39 40 4142 43 44 45 46 47 48 IN1 IN1 IN2 IN2 IN3 IN3 IN4 IN4 IN5 INS IN6 IN6 IN7 IN7 IN8 IN8 OUT1_COLLECTOR OUT1_EMITTER OUT2_COLLECTOR OUT2_EMITTER OUT3_COLLECTOR OUT3_EMITTER OUT4_COLLECTOR OUT4_EMITTER Fig 2 3b Isolated Input Output interface using a 48 pin header connector DM5854HR DM6854HR Page 19 c RTD Finla
3. Input When bit 7 is set to 0 a write can program individual lines of port C D7 0 Active Set Reset Function bit D3 D2 DiI Bit Select 0 0 0 PCO 0 0 1 PC1 0 1 0 PC2 0 1 1 PC3 1 0 0 PC4 1 0 1 PC5 1 1 0 PC6 1 1 1 PC7 J S 1 Set bit to 1 0 Set bit to 0 DM5854HR DM6854HR Page 32 c RTD Finland Oy 1996 2001 Programming the DM6854HR This section gives you some general information about programming the DM6854HR board and then walks you through the major programming functions of the board These descriptions will help you as you use the example programs and function libraries included with this board All of the program descriptions use decimal values unless otherwise specified The DM6854HR is programmed by writing to and reading from the correct I O port addresses of the board These I O ports were described in the previous section of this chapter The following example shows how to perform a 8 bit read and write I O port addresses using C syntax and assembly code Read Write C syntax var inp address outp address data Assembly mov dx address mov dx address in ax dx mov ax data out dx ax Clearing and setting bits in an I O port When you clear or set bits in an I O port you must be careful not to alter the status of other bits You can preserve the status of all the bits you do not wish to change by proper use of the bitwise AND and OR operators Using and or operators single or multiple bits can eas
4. Oy 1996 2001 8255 Mode Definition Bit Set Reset Feature Control Word Control Word D7 D6 D5 D4 D3 D2 D1 D0 D7 D D5 D4 D3 D2 D1 D0 GROUP 2 ee Port C low 17 0 Reset 1 Input one Bit Select 213145 olo mole 1 0 1 1 1 1 0 1 0 0 oO o o o o o Mode Select 0 Mode 0 1 Mode 1 Bit set rst fi GROUP 1 Bit Set Reset Soe ane Port C high 1 Input 0 Output Port A 1 Input 0 Output Mode Select 00 Mode set fla Mode Definition lo Active g DM5854HR DM6854HR Page 24 c RTD Finland Oy 1996 2001 Isolated optocoupler inputs The Isolated input stage of the DM6854HR consists of 4 major parts 1 Output data register 2 Input optocouplers 3 Input bit mask stage 4 Input bit inverter stage 1 Output data register The input circuitry of the DM6854HR consists of a range selection jumper field and an input protection schottky diode The optocoupler is current driven so the input range is selected by connecting different current limiting resistors in series with the optocoupler input diode To protect the optocoupler input diode from overcurrent and reverse voltage a diode is connected in reverse with the optocoupler input
5. PD PU PD FOR PPI PORTS 3 Terminal PULLDOWN IN1 8 INPUT RANGE FOR 3 24V RANGE ISOLATED INPUTS 1 8 Hig Tene Devicer a KANG Oy FIRLAKD aaaaaaaal Figure 1 1 Board layout showing jumper locations DM5854HR DM6854HR Page 8 c RTD Finland Oy 1996 2001 Base Address jumpers Factory setting 300h The most common cause of failure when you are first setting up your module is address contention Some of your computers I O space is already occupied by other internal I O devices and expansion boards When the DM6854HR attempts to use it s reserved I O addresses already used by another peripheral device erratic performance may occur and data read from the board may be corrupted To avoid this problem make sure you set up the base address first using the jumpers marked BASE which let you choose from 32 different I O addresses in your computers I O map Should the factory installed setting of 300H be unusable for your system configuration you may change this setting to another using the options illustrated in Table 1 2 The table shows the switch settings and their corresponding values in hexadecimal values Make sure you verify the correct location of the base address jumpers When you set the base address of the module record the setting in the table inside the back cover of this manual after the Appendices DM5854HR DM6854HR Page 9 c RTD Finland Oy 1996 2001 Table 1 2 Base Address jumper settings A8 A7 A6 A5 A4 Hex Decimal A8 A
6. causes the processor in your computer to temporarily halt its current process and execute another routine Upon completion of the new routine control is returned to the original routine at the point where its execution was interrupted Interrupts are a very flexible way of dealing with asynchronous events Keyboard activity is a good example your computer cannot predict when you might press a key and it would be a waste of processor time to do nothing while waiting for a keystroke to occur Thus the interrupt scheme is used and the processor proceeds with other tasks Then when a keystroke occurs the keyboard interrupts the processor and the processor gets the keyboard data placed it into memory and then returns to what it was doing before the interrupt occurred Other common devices that use interrupts are network boards A D boards serial ports etc Your DM6854HR can interrupt the main processor when an external trigger event occurs if interrupts are enabled on the board By using interrupts you can write powerful code to deal with real world events Interrupt request lines To allow different peripheral devices to generate interrupts on the same computer the PC XT bus has eight interrupt request channels IRQ s A rising edge transition on one of these lines will be latched into the interrupt controller The interrupt controller checks to see if the interrupts are to be acknowledged from that IRQ and if another interrupt is being pr
7. 20h What exactly happens when an interrupt occurs Understanding the sequence of events when an interrupt is triggered is necessary to correctly write interrupt handlers When an interrupt request line is driven high by a peripheral device such as the DM5854 the interrupt controller checks to see if interrupts are enabled for that IRQ and then checks to see if other interrupts are active or requested and determines which interrupt has priority The interrupt controller then interrupts the processor The current code segment CS instruction pointer IP and flags are pushed onto the system stack and a new set if CS and IP are loaded from the lowest 1024 bytes of memory This table is referred to as the interrupt vector table and each entry to this table is called an interrupt vector Once the new CS and IP are loaded from the interrupt vector table the processor starts to execute code from the new Code Segment CS and from the new Instruction Pointer IP When the interrupt routine is completed the old CS and IP are popped from the system stack and the program execution continues from the point it was interrupted Using Interrupt in your Program Adding interrupt support to your program is not as difficult as it may seem especially when programming under DOS The following discussion will cover programming under DOS Note that even the smallest mistake in your interrupt program may cause the computer to hang up and will only restart a
8. 6854HR Page 3 c RTD Finland Oy 1996 2001 This user s manual describes the operation of the DM5854HR DM6854HR Isolated Digital Interface board Some of the key properties of the DM5854HR DM685HR include 8 channel by channel isolated digital inputs with masking modes 4 Optocoupled digital outputs with open collector configuration 30V range 24 non isolated TTL CMOS compatible 8255 based digital I O lines Optional Pull up or Pull down resistors Software enabled interrupts XT and AT interrupts available Single 5V operation Support for direct PC 104 interface with RTD dataModules XT DM5854HR and AT DM6854HR boards available PC 104 compliant RTD IDAN compatible The following paragraphs briefly describe the major features of the DM6854HR A more detailed discussion is included in Chapter 3 Hardware description and in Chapter 4 Board operation and programming The board setup is described in Chapter 1 Board Settings General purpose digital I O The DM6854HR board has 24 8255 based TTL CMOS compatible general purpose digital I O lines which can be directly interfaced with external devices or signals to interface to alphanumerical displays sense switch closures trigger digital events or activate solid state relays These lines may be pulled down or pulled up or pulled down with 10K Ohm resistor networks Installation procedures will be described later in this manual Isolated digital inputs 8 Optocoup
9. 7 A6 A5 A4 2E0 736 01110 3E0 992 11110 2F0 752 01111 3F0 1008 11111 Fig 1 2 Base Address jumper block A4 to top A8 to bottom open lt gt 0 DM5854HR DM6854HR Page 10 c RTD Finland Oy 1996 2001 Interrupt channel Factory setting IRQ5 The header connector shown on Figure 1 3 lets you connect the board interrupt to one of the 6 interrupt channels available on the XT AT bus MH AHH Fig 1 3 Interrupt selection jumpers The interrupt is caused by an external trigger event that has transferred the storage latch data to the output latch of the isolated digital output stage DM5854HR DM6854HR Page 11 c RTD Finland Oy 1996 2001 Pull up or Pull down resistor selection for digital I O PA PB PC Factory setting PA PB and PC pulled down The 8255 programmable digital I O interface provides 24 TTL CMOS compatible lines which can be interfaced with external devices These lines are divided into three groups eight Port A lines eight Port B lines and eight Port C lines You can connect pull up or pull down resistor networks for ports A B and C You may want to pull lines up for connection with switches This will pull the lines high if the switch is disconnected Or you may want to pull lines down for connection to relays which control turning motors on or off The port A B and C lines of the 8255 programmable digital I O interface are set as inputs after reset This can cause the external devices conn
10. 854HR DM6854HR Page 13 c RTD Finland Oy 1996 2001 CHAPTER 2 BOARD INSTALLATION The DM6854HR Isolated digital interface board is very easy to connect to your control system Direct interface to PC 104 systems as well as EUROCARD boards is provided This chapter tells you step by step how to install your board into your system After completing the installation use the diagnostic software to fully verify that your board is working DM5854HR DM6854HR Page 14 c RTD Finland Oy 1996 2001 Board Installation Keep your board in its antistatic bag until you are ready to install it to your system When removing it from the bag hold the board at the edges and do not touch the components or connectors Please handle the board in an antistatic environment and use a grounded workbench for testing and handling of your hardware Before installing the board in your computer check the jumper settings Chapter 1 reviews the factory settings and how to change them If you need to change any settings refer to the appropriate instructions in Chapter 1 Note that incompatible jumper settings can result in unpredictable board operation and erratic response General installation guidelines 1 Turn OFF the power to your computer 2 Touch the grounded metal housing of your computer to discharge any antistatic buildup and then remove the board from its antistatic bag 3 Hold the board by it s edges and install it in an enclosure or place it on the table
11. 8mA 30V Connectors Isolated I O 24 terminal screw terminal connector Optional header connector 48 Pin Non Isolated I O Header connector 50 Pin DM5854HR DM6854HR Page 42 c RTD Finland Oy 1996 2001 NOTES C RTD Finland Oy 1996 2001 DOC DM6854 SAM DM5854HR DM6854HR Page 43 c RTD Finland Oy 1996 2001
12. DM5854HR DM6854HR Isolated digital I O module User s Manual Real Time Devices Finland Oy Real Time Devices Finland Oy Lepolantie 14 FIN 00660 Helsinki Finland Tel 358 9 346 4538 Fax 358 9 346 4539 Email sales rtdfinland fi URL www rtdfinland fi DM5854HR DM6854HR c RTD Finland Oy 1996 2001 ISO9001 and AS9100 Certified IMPORTANT Although the information contained herein has been carefully verified RTD Finland Oy assumes no responsibility for any errors that may occur for any damage to property or persons resulting from improper use of this manual or from the related software RTD Finland Oy also reserves the right to alter the contents of this manual as well as features and specifications of this product at any time without prior notice Published by Real Time Devices Finland Oy Lepolantie 14 FIN 00660 Helsinki Finland Copyright 1996 2001 by RTD Finland Oy All rights reserved Printed in Finland DM5854HR DM6854HR c RTD Finland Oy 1996 2001 Table of Contents INTRODUCTION General purpose digital I O Isolated digital inputs Isolated digital outputs Mechanical description Connector description What comes with your board Board accessories Application software and drivers Hardware accessories Using this manual When you need help CHAPTER 1 BOARD SETTINGS Factory configured jumper settings Base Address jumpers Interrupts and interrupt channels Pull up or Pull
13. SK REGISTER RANGE SELECT IRQ SELECT ISOLATORS PC 104 BUS 4 ISOLATED OUTPUTS 8 ISOLATED DIGITAL INPUTS VO CONNECTOR ADDRESS DECODER amp CONTROL CIRCUITRY Fig 3 1 DM6854HR Block diagram DM5854HR DM6854HR Page 22 c RTD Finland Oy 1996 2001 Digital I O Programmable Peripheral Interface PPI The programmable peripheral interface PPI is used for general purpose digital I O functions This high performance TTL CMOS compatible chip has 24 digital I O lines divided into two groups of 12 lines each Group A Port A 8 lines and Port C upper 4 lines Group B Port B 8 lines and Port C lower 4 lines Port A Port B and Port C are available at the 50 pin expansion connector You can use Ports A B and C in one of these three operating modes Mode 0 Basic I O Lets you use simple input output functions for a port Data is written to or read from the specified port Mode 1 Strobed Input Output Lets you transfer data I O from port A in conjunction with strobed or handshake signals Mode 2 Strobed bi directional input output Lets you communicate with an external device through port A Handshaking is similar to mode 1 Available Port direction definitions Port A may be Inputs or Outputs Port C lower bits may be Inputs or Outputs Port C higher bits may be Inputs or Outputs All these modes are discussed in detail in the 8255 datasheet from Intel DM5854HR DM6854HR Page 23 c RTD Finland
14. diode Make sure you do not exceed the absolute maximum voltage of each nominal input range Exceeding this limit may cause permanent damage to the optocouplers 2 Optocouplers The SMD optocouplers provide the galvanic isolation between the computer and the process signals as well as isolation between input channels The optocouplers are logically non inverting 1 e a voltage on the isolated digital input will be interpreted as a logical 1 To avoid false triggering on the inputs special Schmidt trigger buffers are used to provide reliable and precise switching of the inputs 3 Input bit mask stage The programmable input processing section of the DM6854HR includes an input bit mask filter stage This mask may be is used to select bits or groups of interesting bits for pattern recognition Bit selection is performed by writing to the mask register BA 1 A bit is selected for comparison if it is set to one 1 The currently active mask can be read back from the same address BA 1 After reset condition all bits are 0 and disabled 4 Input bit inverter stage The trigger logic of the DM6854HR uses OR logic from the inputs This means that a transition from low to high on any input will cause a trigger condition To enable bitwise selection of the polarity of the signals an inverter stage may be used Bit inversion is performed by writing to the input inversion register BA 2 An input channel is inverted by writing 1 to the corre
15. down jumpers Isolated input range selection jumpers CHAPTER 2 BOARD INSTALLATION Board installation External I O connections Isolated Input Output Connector 50 pin RTD Expansion Connector CHAPTER 3 HARDWARE DESCRIPTION Digital I O 8255 Programmable digital I O Isolated optocoupler inputs Isolated optocoupler outputs Trigger output Interrupts DM5854HR DM6854HR Page 1 c RTD Finland Oy 1996 2001 CHAPTER 4 BOARD OPERATION AND PROGRAMMING Defining the I O map Base 0 Read digital inputs Clear interrupt Base 1 Digital input mask Base 2 Digital input inversion register Base 3 Control register Digital outputs Base 4 PPI Port A Read Write Base 5 PPI Port B Read Write Base 6 PPI Port C Read Write low and high byte Base 7 PPI Port CW Write Programming the DM6854HR Clearing and setting bits in a port Initializing the 8255 PPI Isolated Digital Input programming Isolated Digital Output programming Trigger Output programming Interrupts What is an interrupt Interrupt request lines 8259 Programmable interrupt controller Interrupt mask register IMR End Of Interrupt EOD Command What exactly happens when an interrupt occurs Using interrupts in your program Writing an interrupt service routine ISR Saving the startup IMR and interrupt vector Common Interrupt mistakes APPENDIX A DM5854HR 6854HR Specifications DM5854HR DM6854HR Page 2 c RTD Finland Oy 1996 2001 List of Illustrations DM5854HR DM
16. ected to these lines to operate erratically Pulling these lines down when the board is powered up the lines will not be active before the 8255 is initialized Figure 1 4 shows both Ports A B and C set in the Pull down configuration Fig 1 4 Pull up and Pull down jumpers for Ports A B and C Inputs pulled down when jumpers in right hand position see above PC4 PC7 Optocoupler isolated inputs Factory setting 24V range The Optocoupler inputs can be jumper configured for different input ranges Each channel can be set for a different range The different ranges use different current limiting resistors at the optocoupler diode input Make sure you set the range correctly since overloading the optocoupler with overcurrent may cause permanent damage to the device All the channels are set in a similar manner Figure 1 5 illustrates one channel set for a 24V level input signal Figure 1 6 illustrates the complete input stage of the DM6854HR The jumper topmost toward the spring loaded connectors selects 5V input range the middle position 12V and the bottom most toward the center of the board 24V The optocoupler forward current is 1OmA for switching max 16mA DM5854HR DM6854HR Page 12 c RTD Finland Oy 1996 2001 Fig 1 5 Optocoupler input range jumpers set for 24V input range rh Pe I rh J J hm mg fag co LO osa fod faced ors ced cag ecaa or d Fig 1 6 Optocoupler input stage layout of the DM6854HR DM5
17. equest to the host computer This feature is especially useful when monitoring for a predefined input condition When this predefined condition occurs an interrupt will indicate this condition to the host This trigger is also available as an external output signal on the 50 pin expansion connector Pin 2 You may use this to trigger other devices or other boards in your system such as the isolated digital output board and DM6854HR The polarity of this trigger signal is programmable and is driven by a tristate buffer This enables several boards to drive the same trigger output signal Interrupts The DM6854HR has an interrupt available to indicate an external trigger This interrupt can be used to tell the host computer that the pre programmed input pattern condition has occurred Chapter 4 will provide programming information on interrupts DM5854HR DM6854HR Page 27 c RTD Finland Oy 1996 2001 CHAPTER 4 BOARD OPERATION AND PROGRAMMING This chapter shows you how to program and use your DM6854HR It provides a complete detailed description of the I O map and a detailed discussion of programming operations to aid you in application programming DM5854HR DM6854HR Page 28 c RTD Finland Oy 1996 2001 Defining the I O Map The I O map of the DM6854HR is shown in Table 4 1 below As shown the module occupies 8 addresses The Base Address designated as BA can be set using the jumpers as described in Chapter 1 Module Settings The followi
18. fter a reboot This can be frustrating and time consuming Writing an Interrupt Service Routine ISR The first step in adding interrupts to your software is to write an interrupt service routine ISR This is the routine that will be executed automatically each time an interrupt request occurs for the specified IRQ An ISR is different from other subroutines or procedures First on entrance the processor registers must be pushed onto the stack before anything else Second just before exiting the routine you must clear the interrupt on the DM6854HR by writing to address BA 0 and write the EOI command to the interrupt controller Finally when exiting the interrupt routine the processor registers must be popped from the system stack and you must execute the IRET assembly instruction This instruction pops the CS IP and processor flags from the system stack These were pushed onto the stack when entering the ISR Most compilers allow you to identify a function as an interrupt type and will automatically add these instructions to your ISR with one exception most compilers do not automatically add the EOI command to the function you must do it yourself Other than this and a few exceptions discussed below you can write your ISR as any code routine It can call other functions and DM5854HR DM6854HR Page 37 c RTD Finland Oy 1996 2001 procedures in your program and it can access global data If you are writing your first ISR we recommend you
19. h the startup IMR saved and the interrupts temporarily disabled you can assign the interrupt vector to point to your ISR Again you can overwrite the appropriate entry in the vector table with a direct memory write but this is not recommended Instead use the DOS function 25h Set Interrupt Vector or if your compiler provides it the library routine for setting up interrupt vectors Remember that interrupt vector 8 corresponds to IRQO vector 9 for IRQ etc If you need to program the source of your interrupts do that next For example if you are using the input compare on the DM6854HR as an interrupt source program it to do that Finally clear the mask bit for your IRQ in the IMR This will enable your IRQ DM5854HR DM6854HR Page 39 c RTD Finland Oy 1996 2001 Common Interrupt mistakes Remember hardware interrupts are from 8 15 IRQ s are numbered 0 7 Forgetting to clear the IRQ mask bit in the IMR Forgetting to send the EOI command after ISR code Disables further interrupts Example on Interrupt vector table setup in C code void far _interrupt new_IRQI1_handler void ISR function prototype define IRQ1_VECTOR 3 Name for IRQ void interrupt far old_IRQ1_dispatcher es ds di si bp sp bx dx cx ax ip cs flags Variable to store old IRQ_ Vector void far _interrupt new_IRQ1_handler void aa na Ree See ee Re AL a a Ser a ee a A ee Function init_irq_handlers Inputs Nothing Returns Nothi
20. ily be set or cleared in one line operations 1 To clear a single bit in a port AND the current value of the port with the value B where B 255 2 exp bit 2 To set a single bit in a port OR the current value of the port with the value B where B 2 exp bit Bits are numbered from 0 7 for the low byte of a word and from 8 15 for the high byte of a word Setting and clearing of multiple bits in a bye or word is more complex 3 To clear multiple bits in a port AND the current value of the port with the value B where B 255 the sum of the values of the bits to be cleared Note that the bits do not have to be consecutive 4 To set multiple bits in a port OR the current value of the port with the value B where B sum of the individual bits to be set DM5854HR DM6854HR Page 33 c RTD Finland Oy 1996 2001 Initializing the 8255 PPI Before you can operate the non isolated general purpose digital I O through the 8255 PPI it must be initialized This step must be performed every time you start up reset or reboot your computer The 8255 PPI is initialized by writing the appropriate control byte to the I O Port BA 7 The contents of your control word will vary depending on how you want to configure your I O lines Use the control word description in the previous I O map section to help you program the right value Example Port A gt Output Port B gt Output Port C Upper gt Input Port C Lower gt Output
21. ler inputs may be used to connect high voltage signals to a computer Eight channel by channel jumper configurable input ranges are available 5V 12V and 24V The optocoupler inputs have a reverse voltage protection diode across the input This enables AC signals to be connected to the isolated optocoupler inputs This input diode also acts as a rectifier The programmable functions of the DM6854HR enable input masking and input pattern recognition with interrupts This relieves the host computer from processor capacity consuming input polling Isolated digital outputs 4 open collector optocoupler outputs may be used to directly drive loads such as switches or relays with voltages up to 30V DC DM5854HR DM6854HR Page 4 c RTD Finland Oy 1996 2001 Mechanical description The DM6854HR is designed on a PC 104 form factor An easy mechanical interface to both PC 104 and EUROCARD systems can be achieved Stack your PC 104 compatible computer directly on the DM6854HR using the onboard mounting holes Connector description There is a 50 pin digital interface connectors on the DM6854HR to directly interface to the non isolated 8255 based digital I O signals The signal definition of this connector is compatible with the digital PC 104 dataModules manufactured by RTD Isolated outputs and inputs are connected to the DM6854HR by either a screw terminal discrete wire connector of with a 50 pin flat ribbon cable header connector Use this type of inte
22. nd Oy 1996 2001 Figure 2 4 shows the 50 pin expansion interface connector layout of the DM6854HR This connector is used to interface to the non isolated 8255 based digital I O signals Pin 1 is away from the PC 104 connector PCO PC1 PC2 PC3 PC4 PCS PC6 PC7 PBO PB1 PB2 PB3 PB4 PBS PB6 PB7 PAO PAI PA2 PA3 PA4 PAS PA6 PAT 5V fused 3 19 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 4 43 45 47 49 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 EXT_TRIGGER OUTPUT DGND DGND DGND DGND DGND DGND DGND DGND DGND DGND DGND DGND DGND DGND DGND DGND DGND DGND DGND DGND DGND DGND DGND DGND Fig 2 4 50 pin expansion interface connector pinout DM5854HR DM6854HR Page 20 c RTD Finland Oy 1996 2001 CHAPTER 3 HARDWARE DESCRIPTION Chapter 3 Hardware Description describes the major features of the DM6854HR the 8255 based digital I O isolated optocoupler inputs isolated optocoupler outputs interrupts and output triggering DM5854HR DM6854HR Page 21 c RTD Finland Oy 1996 2001 Figure 3 1 shows the general block diagram of the DM6854HR This chapter describes the major features of the DM6854HR the 8255 based digital I O isolated optocoupler inputs isolated optocoupler outputs interrupts and output triggering REGISTER INPUT MA
23. ng Purpose Set the pointers in the interrupt table to point to our funtions ie setup for ISR s void init_irq_handlers void _disableQ old_IRQ1_handler _dos_getvect IRQ1_VECTOR 8 _dos_setvect IRQ1_ VECTOR 8 new_IRQ1_handler Gi_old_mask inp 0x21 outp 0x21 Gi_old_mask amp 1 lt lt IRQ1_VECTOR _enable DM5854HR DM6854HR Page 40 c RTD Finland Oy 1996 2001 Function restore do this before exiting program Inputs Nothing Returns Nothing Purpose Restore interrupt vector table l void restore void Restore the old vectors _disableQ _dos_setvect IRQ1_VECTOR 8 old_IRQ1_handler outp 0x21 Gi_old_mask _enable DM5854HR DM6854HR Page 41 c RTD Finland Oy 1996 2001 APPENDIX A DM5854HR DM6854HR Specifications Interface Jumper selectable base address I O mapped Jumper selectable interrupts Digital I O non isolated Number of lines 24 Logic compatibility TTL CMOS Pullup and Pulldown resistors are available Digital inputs isolated Number of lines 8 Input ranges jumper selectable 4 Triggering Voltages 5V range 3 3V approx 12V range 8 5V approx 24V range 20V approx Isolation Voltage 1 500V Rms Optocoupler switching current 10mA Typical 16mA Maximum Digital outputs isolated Number of lines 4 Isolation Voltage 1 500V Rms Output stage Open collector
24. ng sections describe the register contents of each address used in the I O map Table 4 1 DM6854HR I O Map Register Description Read Function Write Function Address in HEX Isolated inputs Digital Inputs 1 8 Clear IRQ trigger BA 0 Input Mask Read input mask Write to mask register BATHI Input Inversion Read input inv reg Write to input inv reg BA 2 Isolated outputs Read conf output reg Write conf output reg BA 3 PPI Port A Reads Port A data Writes Port A data BA 4 PPI Port B Reads Port B data Writes Port B data BA 5 PPI Port C Reads Port C data Writes Port C data BA 6 PPI Control Byte Reserved Writes to Control byte BA 7 BA 0 Digital input register Write The trigger condition is latched on the DM5854 6854 The interrupt request will remain high until the host acknowledges the interrupt This is done with a write to BA 0 Example BA 0 Digital inputs outp BA data Read Clears trigger and interrupt data is irrelevant The eight isolated digital input bits available in connector J4 can be read from address BA 0 DM5854HR DM6854HR Page 29 c RTD Finland Oy 1996 2001 BA 1 Input mask register Write 0 after reset The input mask register selects which bits are monitored for a trigger condition A 1 corresponds to a selected bit This register in located in address BA 1 Example outp BA 1 Ox7F Bits 1 7 are
25. ocessed it decides if the new request should supersede the one in progress or if it has to wait until the one in progress is done The priority level of the interrupt is determined by the number of the IRQ IRQO has the highest priority IRQ7 the lowest Many of the IRQ s are used by the standard system resources IRQO is dedicated for the internal timer IRQ1 is dedicated to the keyboard input IRQ3 for serial port COM2 and IRQ4 for serial port COM1 Often interrupts 5 and 7 are free for the user 8259 Programmable Interrupt Controller The chip responsible for handling interrupt requests in a PC is the 8259 Interrupt Controller To use interrupts you will need to know how to read and set the 8259 s internal interrupt mask register IMR and how to send the end of interrupt EOI command to acknowledge the 8259 interrupt controller Interrupt Mask Register IMR Each bit in the interrupt mask register IMR contains the mask status of the interrupt line If a bit is set equal to 1 then the corresponding IRQ is masked and it will not generate an interrupt If a bit is cleared equal to 0 then the corresponding IRQ is not masked and it can generate an interrupt The interrupt mask register is programmed through port 21h DM5854HR DM6854HR Page 36 c RTD Finland Oy 1996 2001 End of Interrupt EOI Command After an interrupt service routine is complete the 8259 Interrupt Controller must be acknowledged by writing the value 20h to port
26. on an antistatic surface 4 Connect the board to the data acquisition board using the twisted pain 50 pin flat cable Make sure that the polarity of the cable is correct Installation integrated with a PC 104 module stack Secure the four PC 104 installation holes with standoffs Connect the 50 pin expansion connector to your nonisolated digital signals and directly connect your isolated input and output control devices to the onboard I Oconnectors DM5854HR DM6854HR Page 15 c RTD Finland Oy 1996 2001 Isolated Inputs and Outputs 50 PIN EXPANSION CONNECTOR 50 PIN EXPANSION CONNECTOR dataModule PARALLEL CMI4B6SXLC 2 Fig 2 1 DM5854HR integrated with a PC 104 dataModule stack DM5854HR DM6854HR Page 16 c RTD Finland Oy 1996 2001 3U rack or enclosure installation with a EUROCARD CPU with one DM5854HR The PC 104 system can easily be inserted into a 19 rack installation using the CPU as a form factor adapter Assemble your PC 104 dataModules on a RTD single board EUROCARD computer and install the system in a 19 enclosure Multiple DM5854HR boards can easily be connected to this system See figure 2 2 Isolated Inputs and Outputs 50 PIN EXPANSION CONNECTOR dataModule EUROCARD AT 96 CPU WITH PCNO4 EXPANSION BUS Fig 2 2 19 Eurocard rack installation with an integrated PC 104 dataModule and EUROCARD cpuModule computer system DM5854HR DM6854HR Page 17 c RTD Finland Oy 1996 2001
27. ou are writing your ISR in Assembly language DOS and many floating point emulators are not reentrant Of course there are ways to avoid this problem such as those which involve checking if any DOS functions are currently active when your ISR is called but such solutions are beyond the scope of this manual The second major concern when writing ISR s is to make them as short as possible in term of execution time Spending long times in interrupt service routines may mean that other important interrupts are not serviced Also if you spend too long in your ISR it may be called again before you have exited This will lead to your computer hanging up and will require a reboot Your ISR should have the following structure Push any processor registers used in your ISR Most C compiler do this automatically Put the body of your routine here Clear the interrupt bit by writing to address BA 3 Issue the EOI command to the 8259 by writing 20h to address 20h Pop all registers Most C compilers do this automatically 6 DM5854HR DM6854HR Page 38 c RTD Finland Oy 1996 2001 The following C example shows what the shell of your ISR should be like Function new_IRQ_handler Inputs Nothing Returns Nothing Sets the interrupt flag for the EVENT void interrupt far new_IRQ_handler void IRQ_flag 1 Indicate to main process interrupt has occurred Your program code should be here outp BA 0 0x00 Clear
28. rface connector with a TB50 screw terminal block Please consult the factory for more details on different connector options What comes with your board You receive the following items in your DM6854HR package DM5854HR or DM6854HR Isolated digital interface module User s manual Note Latest software and drivers can be downloaded from our website If any item is missing or damaged please call Real Time Devices Finland Customer service department at 358 9 346 4538 Board accessories In addition to the items included in your DM6854HR delivery several software and hardware accessories are available Call your distributor for more information on these accessories and for help in choosing the best items to support your control system Application software and drivers Hardware accessories such as IDAN aluminium enclosure systems For more information in IDAn please visit our websites at www rtdfinland fi and www rtdusa com DM5854HR DM6854HR Page 5 c RTD Finland Oy 1996 2001 Real Time Devices can supply a complete set of accessories to your DM6854HR card These include enclosures power supplies terminal boards TB50 and other interconnection systems Using this manual This manual is intended to help you install your new DM6854HR card and get it running quickly while also providing enough detail about the board and it s functions so that you can enjoy maximum use of it s features even in the most demanding application
29. rite Transfers the 8 bit Port A digital input and output data between the module and an external device A read transfers data from the external device through connector J5 and into port A a write transfers the written data from port A through J5 to the external devices BA 5 PPI PortB Read Write Transfers the 8 bit Port B digital input and output data between the module and an external device A read transfers data from the external device through connector J5 and into port B a write transfers the written data from port B through J5 to the external devices BA 6 PPI Port C Read Write Transfers the 4 bit low nibble of the Port C digital input and output data between the module and an external device A read transfers data from the external device through connector J5 and into bits 0 7 of port C a write transfers the written data bits 0 7 from port C through J5 to the external devices BA 7 PPI Control Byte Write only When bit 7 is set to 1 a write programs the PPI configuration D7 1 Active Mode Set Flag D6 D5 Mode select for group 1 0 0 Mode 0 0 1 Mode 1 1 1 Mode 2 Group 1 D4 0 A Output Direction of Port A 1 A Input D3 0 C upper Output Direction of Port C Upper bits 4 7 1 C upper Input D2 Mode select for group 2 DM5854HR DM6854HR Page 31 c RTD Finland Oy 1996 2001 Group 2 DI 0 B Output Direction of Port B 1 B Input DO 0 C lower Output Direction of Port C Lower bits 0 3 1 C lower
30. s When you need help This manual and all the example programs will provide you with enough information to fully utilize all the features on this board If you have any problems installing or using this board contact our Technical Support Department 358 9 346 4538 during European business hours or send a FAX to 358 9 346 4539 or Email to sales rtdfinland fi When sending a FAX or Email request please include your company s name and address your name your telephone number and a brief description of the problem DM5854HR DM6854HR Page 6 c RTD Finland Oy 1996 2001 CHAPTER 1 BOARD SETTINGS The DM6854HR Isolated digital I O board has jumper settings you can change to suit your application and I O configuration setup The board is factory configured with a 24V input range configuration The factory settings are listed and shown in the diagram in the beginning of this chapter DM5854HR DM6854HR Page 7 c RTD Finland Oy 1996 2001 Factory Configured Jumper Settings Table 1 1 illustrates the factory jumper setting for the DM6864HR Figure 1 1 shows the board layout and the locations of the jumpers The following paragraphs explain how to change the factory jumper settings to suit your specific application Table 1 1 Factory jumper settings see figure 1 1 for detailed locations JUMPER DESCRIPTION NUMBER OF FACTORY SETTING NAME OF JUMPER JUMPERS JUMPERS INSTALLED BASE BASE ADDRESS 5 300h INSTALLED IRQ INTERRUPT CHANNEL 6 5 PU
31. s interrupt on DM6854HR outp 0x20 0x20 Acknowledge the interrupt controller Saving the Startup Interrupt Mask Register JMR and interrupt vector The next step after writing the ISR is to save the startup state of the interrupt mask register IMR and the original interrupt vector you are using The IMR is located in address 21h The interrupt vector you will be using is located in the interrupt vector table which is an array of 4 byte pointers addresses and it is locate din the first 1024 bytes of the memory Segment 0 offset 0 You can read this value directly but it is a better practice to use DOS function 35h get interrupt vector to do this Most C compilers have a special function available for doing this The vectors for the hardware interrupts on the XT bus are vectors 8 15 where IRQO uses vector 8 and IRQ7 uses vector 15 Thus if your DM6854HR is using IRQ5 it corresponds to vector number 13 Before you install your ISR temporarily mask out the IRQ you will be using This prevents the IRQ from requesting an interrupt while you are installing and initializing your ISR To mask the IRQ read the current IMR at I O port 21h and set the bit that corresponds to tout IRQ The IMR is arranged so that bit 0 is for IRQO and bit 7 is for IRQ7 See the paragraph entitled Interrupt Mask Register IMR earlier in this discussion for help in determining your IRQ s bit After setting the bit write the new value to I O port 21h wit
32. selected BA 1 Input mask register Read Performing a read to the input mask register address will return the current data stored in the register BA 2 Input inversion register Write 0 after reset The input inversion register may be used to invert input channels selected by the input mask register If a logical 0 on the input bit is should cause a trigger the respective inversion bit should be set to 1 Example Bits 1 7 are monitored for a condition where any bit changes state from condition Ox3E Step 1 Mask required bits outp BA 1 0x7F O1I11 1111 Step 2 Set inversion register outp BA 2 0x3E 0010 1110 BA 2 Input inversion register Read Performing a read to the input inversion register address will return the current data stored in the register BA 3 Configuration digital output register Write 0 after reset BITO 1 gt External host IRQ enabled 0 gt External host IRQ disabled BITI 1 gt External trigger output 50 pin header pin 2 tristate buffer enabled 0 gt External trigger output tristate buffer in tristate externally pulled low BIT2 1 gt External trigger output active low 0 gt External trigger output active high BITS 3 7 4 bit isolated digital output port BA 3 Configuration digital output register Read Performing a read to this register address will return the current data stored in the register DM5854HR DM6854HR Page 30 c RTD Finland Oy 1996 2001 BA 4 PPI Port A Read W
33. sponding inversion register bit Example outp BA 2 0x0f will invert input channels 1 4 DM5854HR DM6854HR Page 25 c RTD Finland Oy 1996 2001 Isolated optocoupler outputs The Isolated optocoupler output stage of the DM6854HR consists of 3 major parts 1 Output data register 2 Schmidt triggers 3 Optocouplers 1 Output data register The four bit output register holds the output pattern for the output stage Data can be updated and read from address BA 3 bits 4 8 The lower bits 1 4 hold the configuration bits of your DM6854HR Make sure these bits are unchanged when writing to this register To avoid accidental changes in configuration read first data in the register BA 3 before writing to it 2 Schmidt triggers The output of the optocoupler has a Schmidt trigger to condition the output of the optocouplers this will reduce false triggering 3 Optocouplers Small SMD optocouplers are used to isolate each channel of the isolated outputs Individual optocouplers are used for each channel The optocouplers are directly connected to the Output data register The optocouplers are connected in a non inverting configuration in open collector configuration The maximum switching current is 8mA at 30V DM5854HR DM6854HR Page 26 c RTD Finland Oy 1996 2001 Trigger output Your DM6854HR is capable of causing a trigger signal caused by an input condition This trigger output can be programmed to cause a hardware interrupt r
34. stick to the basics just something that enables you to verify you have entered the ISR and executed it successfully For example set a flag in your ISR and in your main program check for the flag Note If you choose to write your ISR in in line Assembly you must push and pop registers correctly and exit the routine with the IRET instruction instead of the RET instruction There are a few precautions you must consider when writing ISR s The most important is do not use any DOS functions or functions that call DOS functions from an interrupt routine DOS is not reentrant that is a DOS function cannot call itself In typical programming this will not happen because of the way DOS is written But what about using interrupts Then you could have the situation such as this in your program If DOS function X is being executed when an interrupt occurs and the interrupt routine makes a call to the DOS function X then function X is essentially being called while active Such cases will cause the computer to crash DOS does not support such operation A general rule is that do not call any functions that use the screen read keyboard input and any file I O routines should not be used in ISR s The same problem of reentrancy exists for many floating point emulators as well meaning you should avoid floating point mathematical operations in your ISR Note that the problem of reentrancy exists no matter what programming language you use Even if y
35. ur DM6854HR The example below illustrates a safe way of controlling the digital outputs Example in C syntax Step 1 store the current contents of the Control Output register reg_data inp BA 3 reg_data holds all information conf_data Ox0f amp amp reg_data mask lower bits to store configuration Step 2 prepare output data stored in variable out_data out_data out_data lt lt 4 shift left 4 bits Step 3 combine configuration and output data and write to port outp BA 3 out_data Il conf_data write to correct address This code can be compressed into more elegant and optimum code The steps above illustrate the logic of operation Trigger output programming As described in the previous sections an external trigger may be used to indicate to the host or other devices that a predetermined input condition has occurred Before you can use an external trigger you must first program your DM6854HkR to enable correct operation The following steps must be taken 1 2 Program the mask and inversion register first here Now we must program the polarity of the trigger output to other devices if this function is used Clear interrupt and trigger register Enable trigger output tristate buffer Enable interrupts this also enables the operation of the external trigger output DM5854HR DM6854HR Page 35 c RTD Finland Oy 1996 2001 Interrupts What is an interrupt An interrupt is an event that
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