Postal scale
Contents
1. clearing the display all appropriately buff ered and 6 lines of keyboard return and an interrupt line as inputs A 5 volt line and return are provided to supply power to the keyboard and display contro logic This arrangement allows up to 48 keys to be scanned by microprocessor 20 using a ccnventional strobe and re turn technique The keys used will be defined i e their meanings mapped by information stored in PROM s 52 so that definitions of keys may be easily changed and an expanded keyboard may be used with the extended postal rate charts and zip to zone information used in more sophisticated models of postal scales Alterna tively the keyboard may be defined by information stored in firmware ROM s 42 In other mailroom equipment such as electronic accounting systems a more elaborate and extensive keyboard may be required Such a keyboard and display would include a keyboard display controller such as the model 8279 manufactured by the above identified Intel Corp To allow for this expansion of keyboard capability the data line may be made bi directional to communicate with the keyboard display controller Preferably the display may be a conventional multiel ement flourescent display High voltage and filament power may be supplied for the display either through connector 70 or locally at the display Remote display connector 80 parallels the display connections of connector 70 providing a data line data clock and a 5 volt2. described in claim 3 wherein said processing means said input means and said weighing means each form a modular subsystem 25 35 40 45 50 55 65 10 5 A postal scale as described in claim 2 wherein said processing means said input means and said weighing means each form a modular subsystem 6 A postal scale as described in claim 5 wherein each of said modular subsystems further comprises a battery connected to a common power bus 7 A postal scale as described in claim 1 wherein said power supply comprises a battery 8 A postal scale as described in claim 7 wherein said processing means said input means and said weighing means each form a modular subsystem 9 A postal scale as described in claim 1 wherein said processing means said input means and said weighing means each form a modular subsystem 10 A postal scale as described in claim 9 wherein each of said modular subsystems further comprises a battery connected to a common power bus 11 A postal scale as described in claim 1 further comprising a general purporse module said module comprising a said processing means b a power supply c first connector means for connecting signals from said weighing means to said processing means and for connecting said power supply to said weighing means d second connector means for connecting signals from said input means to said processing means and for connecting said power supply to said input me
3. said digitized weight to said processing means d a power supply for supplying power to said pro cessing means said input means and said weighing means e power switching means responsive to said pro cessing means for selectively connecting said input means and said weighing means to said power sup ply as necessary to determine said weight and com pute said postage values and then disconnecting said means so as to reduce power requirements and f sensing means for detecting the presence of an item to be mailed on said weighing means and in response initiate the determination of the appropri ate postage for said item by said processing means 2 A postal scale as described in claim 1 wherein said processing means further comprises a a processor for controlling the operation of said scale and for computing said appropriate postage values in accordance with a predetermined pro gram b first memory means connected to said processor for storing said program c second memory means connected to said proces sor for storing postal rate information d second power switching means responsive to said processor for selectively connecting said second memory means to said power supply as necessary to compute said postage values and then discon necting said memory means so as to reduce power requirements 3 A postal scale as described in claim 2 wherein said power supply comprises a battery 4 A postal scale as
4. supply and return to allow for the provision of a remote display The remote display would include its own controller and high voltage and filament supplies Connector 90 is provided to allow connection of the postal scale to a postage meter through a secure com munications link Since the operation of a postage meter is equivalent to the purchase of postage it is critical that the transmission of postage information from the postal scale to the meter be error free A proprietary interface and protocol intended for such error free transmission of postal data to a postage meter is described in U S Pat No 4 301 507 for Electronic Postage Meter Hav ing Plural Computing Systems to Soderberg et al is sued Nov 17 1981 which is hereby incorporated by reference and is known by the trade name Echoplex Connector 90 provides an Echoplex serial data out line 15 20 25 30 35 40 45 50 55 60 65 4 and return a meter trip line which includes special protective circuitry to prevent the generation of false meter trip signals during power on off transients and return and a reset line as outputs Inputs provided are an Echoplex serial data in line a return and an interrupt line A 5 volt line and return are provided to provide a remote reference level for signal detection with re turn Preferably the 4 5 volt line is short circuit pro tected Connector 90 also provides a unregulated 5 volt line which may be
5. used for temporary storage of logged postal data Design of connectors 50 and or 60 to accept either ROM or RAM memory would be a routine task well within the capability of those skilled in the art As described above scale 200 communicates with system 400 through Echoplex connector 90 200 and expander 220 System 40 also communicates through Echoplex connector 400 and may include expander 420 to allow communication with additional scales Device 410 which as indicated above may be a printer or other means for retrieving logged data is connected to module 10 400 through connector 100 400 and appropriate interface circuitry on board 42 400 Non volatile memory 110 400 may contain configu tation parameters such the number of scales connected to system 400 the particular model of printer con nected etc Because an operator may need to exercise greater control over system 400 it includes a general purpose keyboard and display unit 430 which further includes a control unit 432 Control unit 432 communicates with module 10 400 through the bi directional data line of connector 70 400 Because power supply 30 provides power to all the active components on motherboard 10 as well as other 4 649 490 7 components attached to motherboard 10 it must be sized to support the largest system in which it may be used Accordingly to avoid burdening less sophisti cated systems with the cost of an oversized power sup ply FIG 3 shows an embodi
6. 2 and 52 would be selected to provide increased capabilities zip to zone conversion increased postal rate informa tion automatic meter setting extended keyboard defini tions etc In such a system non volatile memory 110 would include calibration constants configuration pa rameters and customer location zip code Programming for postal scales is disclosed in U S Pat No 4 286 325 to Dlugos et al for System And Method For Computing Domestic And International Post age issued Aug 25 1981 and U S Pat No 4 325 440 to Crowley et al for Method And System For Computing Special Fees In A Parcel Postage Metering System issued Apr 20 1982 which are hereby incorporated by refer ence Such programming could readily be translated into firmware for a particular microprocessor by a per son skilled in the art Further the module of the subject invention may also readily be used in mailroom systems such as electronic accounting systems manifest systems mailroom man agement systems or journal printers These systems are well known for use in mailrooms to record records of postal activity for later retrieval For example if the module of the subject invention where intended for use in a journal printer board 42 would be selected to in clude journal printer firmware and printer I O circuitry connected to expansion connector 100 Such a system might well require a full general purpose keyboard and display and use the bi directiona
7. 4 08 02 AYLINIIO Q31VI20SSV ONY Nd9 YOLOSNNOD ONY YOLOANNOD AHOW3W SOVAMALNI NOISNVdX3 3111110A 71V1433S 021 YOLIINNOY ONY 329V4831NI 1135 avo 1VLI910 OE Mdd Ns u3MOd ONY YJWYO4SX 4 649 490 Sheet 2 of 5 U S Patent Mar 10 1987 00 Ol 00 00 2b Ot 00 06 oov oo 29 09 oov loovloovrloor 04 06 00 OM Oev AV1dS10 OBAN d9 zer BTHANI oec AV 1dSIQ Q8AM 3 1V2S WiSOd SMOLV IOSI 00 y3l3aW 39V1SOd 4 649 490 Sheet 3 of 5 U S Patent Mar 10 1987 HOSN3S E c T NOILOW NVd 4 Ob NO123NNO2 auvogadaava WON WON 3HVMWHI J 2s OS NO123NNOO CYVOAFI00Vd WO3d oz WOMNd 31V Ve aie AMLINOUID 9 3NOZ 031VI20SSVY m EIS S ANY nag 29 09 YIMOd OUVOEZIAQVd HOLIINNOI ONY NOISNVdX3 NOISNVIX3 SHINHOAS X 2 Ser SZ S6 U S Patent Mar 10 1987 Sheet4of5 4 649 490 FIG 4 o o i 125 500 4 649 490 Sheet 5 of 5 U S Patent Mar 10 1987 dA1 P89G 4 649 490 1 SCALE WITH PROCESSOR CONTROLLED POWER SWITCHING BACKGROUND OF THE INVENTION Postal scale are well known in the art simple spring scales with scale charts which map a weight range into one or more postal rates having existed for decades More recently with the increased availability of solid state microprocessors load cells and low cost analog to digital A D converters it has become feasible to pr
8. United States Patent 9 Manduley et al 54 75 73 21 22 51 52 58 56 SCALE WITH PROCESSOR CONTROLLED POWER SWITCHING Inventors Flavio Manduley Woodbury Edwin G Grisgraber Huntington both of Conn Assignee Pitney Bowes Inc Stamford Conn Appl No 684 410 Filed Dec 20 1984 Int CL4 nee GO6F 15 20 US CL aret thee 364 466 177 25 364 900 Field of Search 364 464 466 200 MS File 364 900 MS File 177 4 25 323 383 267 References Cited U S PATENT DOCUMENTS 4 180 856 12 1979 Check Jr et al 364 466 vn 364 466 4 430 716 2 1984 Diugos et al 4 472 781 9 1984 Miller 364 466 4 574 352 3 1986 Coppola et al 364 466 4 578 758 3 1986 Muller s 364 466 Primary Examiner Errol A Krass Assistant Examiner H R Herndon DIGITAL LOAD CELL INTERFACE 4 649 490 Mar 10 1987 1 Patent Number 45 Date of Patent Attorney Agent or Firm Robert H Whisker Melvin J Scolnick David E Pitchenik 57 ABSTRACT A computation and control module suitable for use in a variety of postal scales as well as other types of mail room equipment is disclosed The module includes a microprocessor and associated circuitry connectors for connecting ROM which store firmware for controlling the microprocessor and PROM which store postal rate charts an input output connector a serial interface for communicat
9. a corresponding tapped bore 572 is provided at the other end so that a low impedance mechanically strong bus system may be formed by screwing together a plurality of segments 566 Mechani cal and power connections between the subsystems of a battery power system such as that shown in FIG 4 are made by plugging the subsystems into the bus so formed Returning to FIG 4 the power drain on batteries 30 500 515 and 535 may be further reduced by provi sion of switches 25 500 and 125 50 to sequentially con nect subsystems as required substantially in the same manner as described above with respect to the embodi ment of FIG 2 The embodiments of the subject invention described above and shown in the attached drawings have been given by way of illustration only Those skilled in the art will recognize numerous other embodiments within the scope of the subject invention What is claimed is 4 649 490 9 1 A postal scale comprising a processing means for controlling the operation of said scale and for computing appropriate postage values in accordance with the weight of an item to be mailed and postal information entered by an operator said processing means being controlled by a stored program b input means for transmission by said operator of said postal information to said processing means c weighing means for determining the weight of said item to be mailed for converting said weight to digital form and for transmitting
10. and for computing appropriate postage values for an item to be mailed according to its weight and the de sired postal services as specified by information entered by an operator an input for transmission of the informa tion to the processor and weighing apparatus for deter mining the weight of the item converting the weight to digital form and transmitting the digital weight to the processor The scale also includes a power supply for providing power to the processing unit the input and the weighing apparatus The power supply is connected to the input and the weighing apparatus through pro cessor controlled switches for selectively connecting and disconnecting the input and the weighing apparatus to the power supply as necessary to determine the weight of an item to be mailed and its appropriate post age value The processing unit is responsive to a switch or other such device that detects the presence of an item to be mailed on the pan of the weighing apparatus to initiate the computation of the appropriate postage values In another embodiment of the subject invention the processing unit includes a processor a first memory operatively connected to the processor for storing a program to contro the processor and a second memory operatively connected to the processor for storing postal rate information The second memory is con 20 25 30 35 40 45 50 55 65 2 nected to the power supply through a further p
11. ans and e said switching means 12 A postal scale as described in claim 11 wherein Said processing means further comprises a a processor for controlling the operation of said scale and for computing said appropriate postage values in accordance with a predetermined pro gram b first memory means connected to said processor for storing said program c second memory means connected to said proces sor for storing postal rate information d second power switching means responsive to said processor for selectively connecting said second memory means to said power supply for periods necessary to compute said postage value and then disconnecting said memory means so as to reduce power requirements 13 A postal scale as described in claim 12 wherein said processing means said input means and said weighing means each form a modular subsystem
12. by Flavio Manduley filed Mar 19 1984 which is hereby incorpo rated by reference By incorporating battery power on boards 43 52 and 62 additional memory may be added for more sophisticated systems without need for a larger power supply Further incorporating battery power on boards allows preprogrammed RAM s to be shipped to users for postal rate updates etc and the use of only RAM memory with the module of the subject invention mt 0 20 25 30 35 40 45 50 60 65 8 simplifies it use in application such as journal printers and electronic accounting systems where RAM storage is needed With the availability of low power CMOS logic and low power displays it is possible to extend the idea of battery powered modules to encompass entire battery powered modular systems Such a system is shown in FIG 4 A module in accordance with the subject inven tion 10 500 comprises battery powered paddleboards 42 500 and 52 500 a battery power supply 30 500 and incorporates low power CMOS circuitry for active components load cell or other pressure transducer subsystem 510 utilizing low power circuitry 518 for amplifiers and A D s is connected to module 10 500 through connector 120 500 and a low power keyboard and display subsystem 530 is connected through con nector 70 500 Suitable low power load cell subsystems are known in the art and include low power modular load cells manufactured by the Toledo Scale Divisio
13. ions with postage meters a non volatile memory for storing parameters specific to particular units and an auxiliary input output connector The auxiliary input output connector is driven by selected memory mapped interface circuitry mounted on the PROM card The module also includes a load cell inter face and a power supply In one embodiment switches responsive to the microprocessor are provided for se quentially energizing various connectors and interfaces so as to reduce power requirements Systems compris ing a plurality of computation and control modules are disclosed Other systems including battery powered modules mechanically and electrically interconnected by a power distribution bus are also disclosed as a mod ular power bus 13 Claims 5 Drawing Figures 80 REMOTE DISPLAY CONNECTOR KEYBOARD AND DISPLAY CONNECTOR zo EXPANSION CONNECTOR 8716x EXPANSION PADDLEBOARD CPU AND ASSOCIATED CIRCUITRY 20 ZIP ZONE AND RATE CHART RATE PROM PROM PADDLEBOARD CONNECTOR 52 8718K so FIRMWARE ROM ROM CONNECTOR PADDLEBOARD 8724K 42 so 649 490 Sheetlof5 4 1987 10 Patent Mar U S er auvogs1ddvd WON eS auvoga1ddvd WOUd 31V 29 auvog31davd NOISNVdX3 914 YOLOINNOD WOU SJYVMWYlS os 391 8 YOLOSNNOD WOUd LYVHO 31VY ONV 3NOZ dIZ 09 91 8 H01293NNOO NOISNVdX3 OL YOLOSNNOD D AV1dSId QNV QUVOSA3M YOLI3NNOI AW1dS10 310W3
14. l serial communications provided through keyboard and display connector 70 Data would be received through serial interface 90 and in order to retain data for later retrieval random access memory would be provided on paddleboard 62 either through expansion connector 60 and or by replacing PROM s on board 52 FIG 2 shows a mailroom system comprising a postal scale 200 a conventional electronic postage meter 300 and an electronic system 400 Postal scale 200 comprises module 10 200 in accordance with the subject inven tion a load cell subsystem 210 which provides count data for the item weighed through interface and con 10 20 30 35 40 45 50 55 60 65 6 nector 120 200 a port expander 220 connected to Echo plex port 90 200 and a specialized postal scale keyboard and display connected through connector 70 200 Board 42 200 provides firmware which controls mod ule 10 200 in accordance with the desired capabilities In addition to firmware for computing appropriate post age value in accordance with the weight of the item and postal information input through keyboard and display unit 230 board 42 200 also provides firmware for com munications with other systems which may be con nected to scale 200 Such communications firmware is selected by the processor not shown of module 10 200 in accordance with configuration parameters stored in non volatile memory 110 200 In the system shown module 10 200 would co
15. ment of the subject inven tion having a reduced power requirement FIG 3 shows a module which is substantially the same functionally as the module shown in FIG 1 Note that the communications links between subsystems are the same but are not shown in FIG 3 for ease of illustra tion Normally open CMOS switches 55 65 75 95 115 and 125 are connected in series with the 5 volt lines of connectors 50 60 70 90 non volatile memory 110 and connector 120 reducing the stand by power drain on power supply 30 Switch assembly 25 connects the 5 volt source to an interrupt input of microprocessor 20 and is actuated either mechanically electro optically or in some other suitable manner by motion of the scale pan not shown In response to the interrupt micro processor 20 would command power control circuit 130 to close switch 125 to energize the load cell subsystem not shown and digital load cell interface 120 so that the weight counts from the load cell subassembly can be generated and transmitted When a stable count input is received switch 125 is opened and switch 115 closed so that the parameters stored in non volatile memory 110 may be retrieved Switch 115 is then opened and switch 75 is closed so that the operator may enter the necessary information for the item to be mailed Note that prefer ably a separate unswitched 5 volt source 72 is also provided to connector 80 to keep the keyboard of the keyboard display unit not sho
16. mmunicate with a conven tional postage meter 300 which may be a meter such as the Model 6500 meter manufactured by Pitney Bowes Inc Stamford Conn and electronic system 400 In addition to transmitting postage values and trip signals to meter 300 module 10 200 also transmits postal infor mation such as postage value weight destination zip code etc to electronic system 400 Board 52 200 provides appropriate postal rate infor mation and zip to zone information for scale 200 and also provides information defining the keys of keyboard display unit 230 which is read by a conventional strobe and return technique through connector 70 200 System 400 may be any of a number of mailroom systems for logging postal data such as electronic ac counting systems journal printers mailroom manage ment systems etc Such systems also provide for later retrieval of the data either by printer downloading to a disk computer interface or other means Such a system is shown in FIG 4 based on module 10 400 which is structurally identical to module 10 200 Board 42 400 provides firmware which defines the data logging and system control functions Such program ming would essentially involve no more than simple data base management and routine housekeeping functions for the system shown and would be well within the skill of those skilled in the art Boards 52 400 and or 62 400 would connect RAM memory to module 60 400 Such RAM storage may be
17. n of Reliance Electric Co Worthington Ohio capaci tance transducers manufactured by Serta Corp Massa chusetts and Digital Mass Transducers manufactured by K Tron Arizona Corp Scottsdale Ariz Similarly low power displays and keyboards are available rang ing up to the typewriter type keyboard and multiline display used in the current generation of laptop com puters Each subsystem includes its own battery power sup ply 515 and 535 again so that battery 30 500 need not be sized to supply the largest system contemplated Batteries 30 500 515 and 535 are interconnected by a low impedance external power bus 550 to reduce noise problems and also to mechanically interconnect the subsystems Bus 550 is formed from a plurality of substantially identical segments 560 shown in FIG 5 Segment 560 comprises two substantial low impedance conductors 562 and 564 for 5 volts and ground respectively Conductors 562 564 are held in parallel fixed relation ship by substantially rigid separator 566 Spaced along conductors 562 and 564 are polarized sockets 568a and 568b into which various battery powered subsystems may be plugged The sockets are spaced closely enough that multiple connections may be made by each subsys tem in order to minimize noise problems The ends 562m 562 564m and 564 are shaped to mate with the corresponding ends of similar segments 560 At one end of separator 566 a captive thumbscrew 570 is mounted and
18. oard supports the various components and connectors comprising the subject computation and control module An integrated circuit microprocessor and its associated support cir cuitry are mounted on motherboard 10 to provide intel ligence i e programmable general purpose computa tion and control capabilities for the subject module Such microprocessors are well know to those skilled in the art Typical of such microprocessors is the well known Intel Model 8085 manufactured by the Intel Corp Santa Clara CA Descriptions of the architec tural structure of the 8085 and procedures for opera tionally connecting such microprocessors with various memory and input output devices may be found in MCS 80 85 Family User s Manual published by Intel Corp 1979 Similar microprocessors and information are available from other manufacturers and are well known to those skilled in the art Accordingly detailed description of the microprocessor its associated cir cuitry and its interface to other components is unneces sary to an understanding of the subject invention and will not be discussed further Connectors 40 50 60 are connected to microproces sor 20 to allow the easy connection of memory modules to microprocessor 20 the term connector as used herein is meant to include both single connectors or groups of connectors used together to perform a func tion Similarly paddle boards and other sub modules may comprise single units or groups
19. of related units Connector 40 allows 8K to 24K bytes of read only memory ROM mounted on paddleboard 42 to be con nected to microprocessor 20 This memory is used to store the firmware used to control the postal scale or 4 649 490 3 other item of postal equipment comprising the subject module Connector 50 allows 8K to 16K bytes of pro grammable read only memory PROM mounted on paddleboard 52 to be connected to microprocessor 20 This memory is used to store postal rate charts and zip to zone information which information is used to convert zip codes to postal zones for computing post age PROM s are preferred for storing postal rate data since such data is subject to fairly frequent change However those skilled in the art will recognize that once programmed PROM s and ROM s are function ally the same Thus hereinafter while recognizing that either PROM s or ROM s may be used PROM s will refer to postal rate and zip to zone memory while ROM s will refer to firmware memory Connector 60 allows 8K to 16K of additional memory ROM or PROM to be connected to microprocessor 20 to pro vide an expansion capability for larger systems Connector 70 is provided to allow microprocessor 20 to communicate with a keyboard and display not shown to provide an operator interface Connector 70 provides as outputs a serial data line a serial clock line 3 lines of encoded keyboard strobe signals and a reset signal for
20. ovide electronic digital postal scales with greatly increased capabilities These increased capabilities have not been without price however and part of this price has been an increasing demand placed on scale power supplies as capabilities were expanded This problem is further aggravated by any attempt to increase the com monality of components used in a family of scales and other mailroom products as disclosed in the commonly assigned U S patent application entitled General Pur pose Processor Module Mailroom Equipment by Flavio Manduley filed Dec 20 1984 Ser No 684 411 since clearly any common power supply must be capa ble of meeting the greatest peak demand in its product family Thus it is an object of the subject invention to pro vide an electronic scale having reduced peak power demands It is another object of the subject invention to provide an electronic postal scale of modular design which may be expanded to an increased capacity without an in crease in the size of the power supply provided Other objects and advantages will be readily appar ent to those skilled in the art from consideration of the detailed description set forth below and of the attached drawings BRIEF SUMMARY OF THE INVENTION The above objects are achieved and the disadvan tages of the prior art are overcome in accordance with the subject invention by means of a scale comprising a processing unit for controlling the operation of the scale
21. rocessor controlled switch for selectively connecting and dis connecting the second memory as necessary to compute the appropriate postage value The subject invention advantageously supplies a scale having a reduced peak power demand wherein various subsystems of the scale are energized under processor control only as need to determine the appropriate post age value Other objects and advantages of the subject invention will be readily apparent to those skilled in the art from consideration of the detailed description set forth below and of the attached drawings BRIEF DESCRIPTION OF THE DRAWINGS FIG 1 shows a schematic block diagram of a compu tation and control module for use in postal scales and other mailroom equipment FIG 2 shows a schematic block diagram of a mail room system FIG 3 shows a schematic block diagram of a compu tation and control module substantially similar to that shown in FIG 1 which further shows power switching arrangements used to reduce power requirements FIG 4 shows a schematic block diagram of a modu lar battery powered mailroom system FIG 5 shows a plan view of a power bus module DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION FIG 1 shows a computation and control module for use in postage scales and other mailroom equipment such as electronic accounting systems in accordance with the subject invention A large printed circuit board 10 commonly known as a motherb
22. such as electrically erasable programmable read only memory E PROM s This memory is dis cussed separately from other memory since it is used to store data which is peculiar to particular scales lt is used to store information such as load cell calibration constants e g zero correction factors configuration parameters e g meter in use automatic set mode and customer location zip code for zip to zone conver sion Preferably this data will be stored with redun dancy so that errors may be detected and possibly corrected It is also preferred that the data be electri cally alterable so that it may be changed or corrected through microprocessor 20 Digital interface and connector 120 is provided to allow transmission of raw digital data from the load cell transducers after conversion by the associated analog to digital converter A D Details of the design of this interface would depend on the particular load cell and associated circuitry chosen for the load cell but would be well within the abilities of those skilled in the art Numerous patents including U S Pat Nos 4 139 892 and 4 350 216 show techniques for interfacing load cells to microprocessors Having selected a particular inter face design and protocol it would be routine for a per son skilled in the art to adapt it to a product family of scales essentially requiring only the provision of a suffi cient number of data bits to allow the desired precision thro
23. ugh the whole family of scales 4 649 490 5 Preferably the load cell subsystem includes its own control processor This would aliow the load cell raw digital data commonly known as counts to be transmit ted with error detection correction redundancy check sums etc and two way communications to check Status request retransmission in the event of an error etc Further incorporation of a microprocessor into the load cell subsystem would reduce the design of inter face 130 to a routine processor to processor communi cations problem In use the function of the module of the subject inven tion would be controlled by the selection of ROM pad dleboard 42 PROM paddleboard 52 and the informa tion stored in non volatile memory 110 For example if the module of the subject invention were intended for use in a low range unsophisticated scale with limited keyboard and display capabilities board 42 would be chosen lacking input output circuitry and with ROM s programmed with firmware appropriate for the in tended unsophisticated application Board 62 would be selected with PROM s defining a limited selection of postal rates and defining a limited keyboard In a very unsophisticated system zip to zone information might be entered through the keyboard In such a system non volatile memory 110 would only include load cell calibration constants and no zip to zone conversion tables would be provided In a more sophisticated system boards 4
24. used to provide power to a two port interface expansion module mounted on a separate board In more sophisticated scales such a board allows communication with a postage meter and with devices such as electronic accounting systems t should be noted that the Echoplex circuitry pro vided in the module of the subject embodimient does not include optoisolators but relies on the isolators of the connected postage meter However the two port expansion board may preferably include a port with isolators for communication with devices such as elec tronic accounting systems which may not include isola tors Connector 100 is provided to allow input output expansion A number of undefined lines are connected from firmware connector 40 to connector 100 This allows additional input output circuitry to be mounted on ROM paddleboard 42 Thus for example a field upgrade of a postal scale to provide a printer output may be achieved simply by changing paddleboard 42 the substitute board would not only include firmware to control the printer but also input output circuitry which would provide a printer port at connector 100 Those skilled in the art will recognize that since micro processors such as the 8085 use memory mapped 1 0 where input output registers are addressed as memory locations input output circuitry mounted on paddle board 42 is directly accessable to microprocessor 20 Non volatile memory 110 comprises a small amount of memory
25. wn live so that opera tion of the scale may also be initiated from the key board Switch 75 is then opened and switch 50 and if necessary switch 60 are closed to energize boards 52 and 62 so that necessary postal rate information and zip to zone conversion information may be retrieved The appropriate postage value for the item to be mailed is then determined by microprocessor 20 and switches 55 and 65 are opened If the configuration parameter information retrieved from non volatile memory shows a postage meter connected switch 95 is closed to ener gize the Echoplex interface and connector 90 for trans mission of the postage value information to such meter Switch 75 is then opened and microprocessor 20 returns to a wait state until the next interrupt or command from the keyboard Thus the peak power demands on supply 30 are substantially reduced allowing use of a smaller less costly supply In less sophisticated systems with low peak power requirements power controller 130 may be omitted and switches 55 65 75 95 115 and 125 may be replaced where necessary with jumpers to reduce the cost of the module and to simplify the firmware In another embodiment of the subject invention the ROM s and PROM s of boards 42 52 and 62 may be replaced with battery powered memory modules Such modules are disclosed in commonly assigned U S pa tent application Ser No 590 670 for Postal Rate Mem ory Module with Integral Battery Power
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