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Not Recommended for New Installations.
Please contact Technical Support for more information.
Parallel Port Input/Output Converter
Model PPIO
Document No. PPIO2899
B&B Electronics Mfg. Co. Inc.
707 Dayton Road -- P.O. Box 1040 -- Ottawa, IL 61350 USA
Phone (815) 433-5100 -- General Fax (815) 433-5105
Home Page: www.bb-elec.com
Sales e-mail: orders@bb-elec.com -- Fax (815) 433-5109
Technical Support e-mail: support@bb.elec.com -- Fax (815) 433
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TABLE OF CONTENTS INTRODUCTION .............................................................................1 PACKING LIST.................................................................................2 PC PARALLEL PORT DESCRIPTION ...........................................3 PPIO DESCRIPTION & CONNECTION..........................................7 CONTROLLING THE PPIO USING GWBASIC..............................9 CONTROLLING THE PPIO USING PASCAL...............................12 CONT
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INTRODUCTION The PPIO allows you to connect your IBM PC (or clone) computer to the outside world using the computer’s parallel port. The eight I/O points can be used as either inputs or outputs. As an output they can control voltages as high as 50 Volts DC and can handle currents as high as 500 mA DC. As an input they can handle voltages from 0 to 50 volts with a threshold of 2.5 Volts DC. CAUTION: Each output of the PPIO can dissipate 1 Watt when used alone, however, all eight
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Packing List Examine the shipping carton and contents for physical damage. If there is damage, contact B&B Electronics immediately. The following items should be in the shipping carton: 1) PPIO unit 2) This Instruction Manual 3) PPIO Sample/Test Disk If any of the above items is missing contact B&B Electronics immediately. 2 PPIO2899 Manual B&B Electronics Mfg Co Inc – 707 Dayton Rd - PO Box 1040 - Ottawa IL 61350 - Ph 815-433-5100 - Fax 815-433-5104
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PC PARALLEL PORT DESCRIPTION To understand how the PPIO can be controlled you must first understand how the parallel port works inside the computer. The parallel port is designed to connect the computer with the outside world. It can have up to 12 TTL compatible outputs and up to 9 TTL compatible inputs. It cannot have both at the same time since some inputs and outputs share pins. Eight of the outputs and five of the inputs are dedicated. Four of the lines can be either inputs or o
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used to read the status of the port. The PPIO does not need to use this port as an input port. Again, referring to Table 1, if you input the data on port 0379H, then whatever TTL level pins 15, 13, 12, 10, and 11 are will show up as bits 3 through 7. The state of bits 0, 1, and 2 will be unknown since they are not hooked to anything, but they probably will be HIGH (ONE). Note that the data on pin 11 will be inverted, if pin 11 is LOW you will get a HIGH on bit 7. The pins with the “bar
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378H 379H 37AH Output Input Output Input Output Input BIT _ _ 0 2 2 X X 1 1 _ _ 1 3 3 X X 14 14 2 4 4 X X 16 16 _ _ 3 5 5 X 15 17 17 See See 4 6 6 X 13 Note 2 Note 2 5 7 7 X 12 X X 6 8 8 X 10 X X _ 7 9 9 X 11 X X Table 1 Note 1: X means no connection to any DB-25 pin. Note 2: Bit 4 of 37AH as an output is used to control the interrupt IRQ7. When this bit is HIGH, IRQ7 is enabled and when this bit is LOW, IRQ7 is d
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There are three port addresses that are normally used on a PC for parallel ports: 3BCH, 378H, and 278H. When your PC is reset or turned on these three addresses are scanned by the BIOS in the order shown above. The first one that the BIOS finds with a parallel port installed is assigned the logical name LPT1. The second, LPT2, etc. You can connect the PPIO to a port located at any of these three addresses. During power up the computer will assign that port a logical name but we will
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PPIO DESCRIPTION & CONNECTION The PPIO makes use of the eight output pins (pins 2 through 9) at address 378H to drive its eight outputs. It uses the upper four bits of address 379H (pins 13, 12, 10, and 11) for the upper four input bits of the PPIO. It uses the lower four input bits of address 37AH (pins 1, 14, 16, and 17) for the lower four input bits of the PPIO. This assumes you are using the same port addresses as in Table 1. In this way the PPIO can have eight inputs or eight out
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Figure 1 8 PPIO2899 Manual B&B Electronics Mfg Co Inc – 707 Dayton Rd - PO Box 1040 - Ottawa IL 61350 - Ph 815-433-5100 - Fax 815-433-5104
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CONTROLLING THE PPIO USING GWBASIC Refer to the fragment of GWBASIC code in Figure 2 to see how to input the bits and make one 8-bit word. 100 OUT &H37A,&H04: REM This disables the 37AH Outputs 120 REM inside of the computer 140 REM so that we can use 160 REM 37AH as an input port. 180 REM It also disables 200 REM the IRQ7 interrupt. . . 300 A1=INP(&H37A) AND &H0F: REM Input the 320 REM lower 4 bits 340 REM and mask OF
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I/O Bit Force I/O ON Force I/O OFF (Low) (High) 0 OR &H01 AND NOT &H01 1 OR &H02 AND NOT &H02 2 OR &H04 AND NOT &H04 3 OR &H08 AND NOT &H08 4 OR &H10 AND NOT &H10 5 OR &H20 AND NOT &H20 6 OR &H40 AND NOT &H40 7 OR &H80 AND NOT &H80 Table 2 The big advantage of using the ANDing and ORing as shown in Table 2 is that it makes each PPIO pin independent. If you have, for instance, PPIO bit 2 ON and all of the rest of the bits OFF then your variable OB will be equal to 04H (00000100
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When you input the 8-bit word using lines 300-460 of Figure 2, note that you also get the status of the outputs. If some I/O bits are used by the PPIO as outputs the status of the bits you read will tell you the status of the PPIO outputs. If PPIO output bit 0 is LOW then bit 0 of IB (the variable InputByte) will be HIGH (1). This can be used to check that the PPIO hardware is connected and is working properly. If, through a fault, a PPIO bit is shorted to ground then, when you rea
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CONTROLLING THE PPIO USING PASCAL The PPIO disk includes two source code files as an example of using the PPIO with the Pascal programming language. PPIO.PAS is the main routine of the example program. PPIOUNIT.PAS contains the routines for communicating with the PPIO. In the rest of this section, we assume that you know the Pascal programming language. Consult your reference manuals if you need help with the language. The Pascal Unit, PPIOUNIT.PAS handles communication with the pa
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PROCEDURE Set_IRQ_Off; BEGIN PORT[Control_Address] := $04;{Write 4 to disable IRQ} END; {Set_IRQ_Off} The function, In_Byte, returns the value of the variable, Input_Byte. It is defined as: FUNCTION In_Byte : Byte; BEGIN In_Byte := Input_Byte; End; { In_Byte } Notice that this does not read the value of the parallel port. The function Read_Input_Bit reads the port. The function, Out_Byte, returns the value of the variable Output_Byte. It is defined as: FUNCTIO
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The parallel port’s status register stores the upper nibble (four bits) of the input line status. Since the smallest value that can be read from the port is a byte, some work must be done to get only the upper nibble’s value. We read a byte from the status register and bitwise AND it with F0h (240 decimal, 11110000 binary). This sets the lower nibble of the byte to zero. The parallel port’s control register stores the low nibble of the input line status. A method, similar to the one
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Notice that in the binary representation of the mask value, line zero’s mask has bit number zero set, and line one’s mask has bit number one set, etc. So, instead of retrieving the mask value from a table, the value is calculated by shifting 00000001b (1 decimal, 01 hexadecimal) right the same number of times as the desired line number. Once the mask value is calculated, it is bitwise ANDed with Input_Byte. If the resulting value is non-zero, the line is ON and a boolean TRUE is ret
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As with the function, In_Byte, the mask value is calculated by shifting 00000001b right the same number of times as the desired line number. Once the mask value is calculated, it is bitwise ANDed with Output_Byte. If the resulting value is non-zero, the line is ON and a boolean TRUE is returned, otherwise a boolean FALSE is returned. Notice that this function gets its value from Output_Byte that is set when we use the function, Set_Output_Bit. The value is not read from the port. Fo
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For example: Output_Byte = 01010101b Line_Number = 3 Status = 1 00000001b (1 decimal) shift-right 3 (Line_Number) = 00001000b XOR 11111111b 11110111b (mask 1) AND 01010101b (Output_Byte) 00000001b (Status) 01010101b shift-right 3 (Line_Number) = OR 00001000b (mask 2) 01011101b (New Output_Byte) For an example of an application that uses these functions, look at the source code in PPIO.PAS. 17 PPIO2899 Manual B&B Electronics Mfg
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CONTROLLING THE PPIO USING C The PPIO disk includes three source code files as an example of using the PPIO with the C programming language. PPIO.C is the main routine of the example program. PPIOFUNC.C contains the routines for communicating with the PPIO. PPIOFUNC.H contains the function prototypes and definitions for use by PPIOFUNC.H and PPIO.C. In the rest of this section, we assume that you know the C programming language. Consult your reference manuals if you need help with the l
