Abstract:
A precision air planter for plot planting includes a metering unit with separate seed systems which may be selectively activated to allow alternately planting various seed types from one plot to the next. A rotary encoder provides location information which is used by a microprocessor to calibrate the system, control seed planting and spacing, control plot length and spacing and record data related to the planted plots.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of the prior filed, application Serial No. 60/251,978, filed Dec. 6, 2000, entitled PRECISION AIR PLANTER FOR PLOT PLANTING. 
    
    
     BACKGROUND OF THE INVENTION 
     The use of seed planters for agricultural purposes is well known. Seed planters are typically used to plant a row or entire field of a single type of seed. In research applications, it may be necessary to plant seeds of different types within the same field in plots of the same seed type. In the research environment, it is often necessary to precisely record the number of seeds planted and the location of each seed. It is necessary to separate different types of seed to avoid cross contamination. From plot to plot the seeds must be cleaned out and the next type of seed loaded in the planter for the next plot. 
     Another problem with prior art planters is the calibration of the planter is done once at the beginning of the day and then allowed to drift. By the end of the day, the spacing of the planted seeds may be significantly different than the spacing at the beginning of the day. 
     SUMMARY OF THE INVENTION 
     A primary object of the present invention is to provide an air planter having multiple seed systems on one plate. 
     Another important object of the present invention is to provide an air planter as aforesaid which separates the seed systems on the seed plate to ensure no cross-contamination between the seeds. 
     Still another object of the present invention is to provide an air planter as aforesaid having independently controlled vacuum cutoff to the seed plate in order to control the start and stop of the plots. 
     Yet another object of the present invention is to provide an air planter as aforesaid that allows the seed to be in contact with the seed plate or positioned very close to the seed plate while the seed is waiting for the start of the plot. 
     Still another object of the present invention is to provide an air planter with multiple seed systems on one plate having separated agitation grooves or ribs for seed agitation. 
     Another important object of the present invention is to provide an air planter that is computer controlled and monitored to ensure proper seed flow. 
     Yet another important object of the present invention is to provide an air planter as aforesaid in which all user configured variables may be input to the computer. 
     Still another important object of the present invention is to provide an air planter as aforesaid which calibrates itself continuously while operating by checking its calculated position against a known location such as a check cable ball, a GPS signal, a laser positioning system, an ultrasonic signal, an infrared signal, or a pre-measured and pre-marked field. 
     Yet another important object of the present invention is to provide an air planter as aforesaid that suppresses error checking functions at non-critical times such as between passes while the planter is turning around and not planting and re-enables error checking automatically before the start of the next planting pass. 
     Another important object of the present invention is to provide an air planter as aforesaid which senses the seed on the plate before it enters the seed tube to provide more accurate seed counts. 
     Still another important object of the present invention is to provide an air planter as aforesaid in which the signal from the seed sensor in the drop tube is filtered and made into a consistent signal before being sent to the computer and analyzed as a seed to be counted and not mistaken as debris. 
     Yet another important object of the present invention is to provide an air planter as aforesaid which includes a pressurized seed tube to limit dust in the seed tube to help ensure more accurate seed counts. 
     Other objects and advantages of this invention will become apparent from the following description taken in connection with the accompanying drawings wherein is set forth by way of illustration and example, an embodiment of this invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a diagram illustrating the air planter of the present invention coupled to a tractor. 
     FIG. 2 is a side view of the planter showing the metering unit. 
     FIG. 3 is a perspective view of the vacuum unit. 
     FIG. 4 shows the inside of the programmable logic controller (PLC) enclosure showing the PLC, the I/O interface, the power transformers, and the level detection circuit. 
     FIG. 5 is a perspective of the air planter looking rearwardly. 
     FIG. 6 shows spaced-apart seeds planted in a trench. 
     FIG. 7 shows the cable guide. 
     FIG. 8 a  is a front perspective illustration of an assembled metering unit. 
     FIG. 8 b  is a rear perspective illustration of an assembled metering unit. 
     FIG. 9 a  is a front perspective exploded drawing of FIG. 8 a.    
     FIG. 9 b  is a rear perspective exploded drawing of FIG. 8 b.    
     FIG. 10 is a perspective view of a diverter block. 
     FIG. 11 is a front elevation view of the diverter of FIG.  10 . 
     FIG. 12 is a side elevation view of the diverter of FIG.  10 . 
     FIG. 13 is a sectional view taken along line A—A of FIG.  12 . 
     FIG. 14 is a mounting bracket for the diverter of FIG.  10 . 
     FIG. 15 is a perspective view of the seed tube block. 
     FIG. 16 is a top view of the seed tube block of FIG.  15 . 
     FIG. 17 is a front elevation view of the seed tube block of FIG.  15 . 
     FIG. 18 is a cross-sectional view taken along line A—A of FIG.  17 . 
     FIG. 19 is a rear elevational view of the seed tube block of FIG.  15 . 
     FIG. 20 is a front perspective view of the seed tube block diverter. 
     FIG. 21 is a rear perspective view of the seed tube block diverter of FIG.  20 . 
     FIG. 22 is a rear elevational view of the seed tube block diverter of FIG.  21 . 
     FIG. 23 is a perspective view of the inner seed sump. 
     FIG. 24 is a front elevational view of the inner seed sump of FIG.  23 . 
     FIG. 25 is a top view of the seed sump of FIG.  23 . 
     FIG. 26 is a side elevational view of the seed sump of FIG.  23 . 
     FIG. 27 is a front elevational view of the cover plate. 
     FIG. 28 is a perspective view of the divider vane. 
     FIG. 29 is a front elevational view of the divider vane of FIG.  28 . 
     FIG. 30 is a rear elevational view of the divider vane of FIG.  28 . 
     FIG. 31 is a sectional view of the divider vane of FIG.  29 . 
     FIG. 32 is a perspective view of the inner singulator. 
     FIG. 33 is a rear elevational view of the singulator of FIG.  32 . 
     FIG. 34 is a front elevational view of the singulator of FIG.  32 . 
     FIG. 35 is a perspective view of the outer singulator. 
     FIG. 36 is a rear elevational view of the singulator of FIG.  35 . 
     FIG. 37 is a front elevational view of the singulator of FIG.  35 . 
     FIG. 38 is a perspective view of the singulator adjuster. 
     FIG. 39 is a perspective view of the seed ejector. 
     FIG. 40 is a front elevational view of the dual ring seed plate. 
     FIG. 41 is a perspective view of the vacuum seal plate. 
     FIG. 42 is a rear elevational view of the vacuum seal plate of FIG.  41 . 
     FIG. 43 is a perspective view of the inner vacuum cutoff shoe. 
     FIG. 44 is a perspective view of the outer vacuum cutoff shoe. 
     FIG. 45 is a perspective view of the vacuum cutoff solenoid mount. 
     FIG. 46 is a perspective view of the vacuum ring. 
     FIG. 47 is an electrical schematic of a PLC I O interface circuit. 
     FIG. 48 is an electrical schematic of the PLC interface. 
     FIG. 49 is an electrical schematic of the signal conditioning and monitoring board sensor. 
     FIG. 50 is a software flow chart of the PLC startup menu. 
     FIG. 51 is the PLC solenoid and sensor check software flow chart. 
     FIG. 52 is the upload plot numbers PLC software flow chart. 
     FIG. 53 is the download stored data PLC software flow chart. 
     FIG. 54 is the change setup software flow chart. 
     FIG. 55 is the calibrate software flow chart. 
     FIGS. 56 through 59 are the plant mode software flow charts. 
     FIG. 60 is the position monitor and calibration software flow chart. 
     FIG. 61 is a diagrammatic illustration of a row plot. 
     FIG. 62 illustrates the position of the seed metering unit before the first plot start. For the outer seed ring, the vacuum cutoff shoe is closed, the seed sump is closed and the seed is in the sump. For the inner ring, the vacuum cutoff shoe is closed, the seed sump is closed, and no seed is in the sump. No seed is on the plate and the diverter is towards the outer ring. 
     FIG. 63 illustrates the seed metering unit configuration after the first plot start. For the outer seed ring, the vacuum cutoff shoe is open, the seed sump is closed and there is seed in the sump. For the inner seed ring, the vacuum cutoff shoe is closed, the seed sump is closed and seed is in the sump. Seed is on the outer ring of the seed plate and the diverter is pointed toward the inner ring. 
     FIG. 64 illustrates the seed metering unit configuration after the first cleanout to allow spacing for the first alley. For the outer seed ring, the vacuum cutoff shoe is open, the seed sump is open and no seed is in the sump. For the inner seed ring, the vacuum cutoff shoe is closed, the seed sump is closed and seed is in the sump. There is seed on the outer seed ring of the seed plate and the diverter is pointed toward the inner seed ring. 
     FIG. 65 is a side view the configuration shown in FIG.  64 . 
     FIG. 66 illustrates the configuration of the seed metering unit at the start of plot  2 . For the outer ring, the vacuum cutoff shoe is closed, the seed sump is closed, and there is seed in the sump. For the inner seed ring, the vacuum cutoff shoe is open, the seed sump is closed, and there is seed in the sump. There is seed on the end of the outer seed ring of the seed plate and seed is beginning on the inner ring of the seed plate. The diverter is pointed toward the outer seed ring. 
     FIG. 67 illustrates the configuration of the seed metering unit at the end of plot  2  to allow spacing for the second alley. For the outer seed ring, the vacuum cutoff shoe is closed, the seed sump is closed and seed is in the sump. For the inner seed ring, the vacuum cutoff shoe is open, the seed sump is closed and no seed is in the sump. There is seed on the inner ring of the plate and the diverter is pointed toward the outer seed ring. 
     FIG. 68 is a side view of FIG.  67 . FIG. 69 illustrates the configuration of seed metering unit after the start of plot  3 . For the outer seed ring, the vacuum cutoff shoe is open, the seed sump is closed and there is seed in the sump. For the inner seed ring, the vacuum cutoff shoe is closed, the seed sump is closed and there is seed in the sump. There is seed at the end of the inner ring and seed beginning on the outer ring of the seed plate. The diverter is pointed towards the inner seed ring. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Turning more particularly to the drawings, FIGS. 1 and 5 show a vacuum planter  100  of the present invention which is pulled behind tractor  102 . Vacuum planter  100  may plant one to four rows or more rows simultaneously. Planter  100  uses a conventional planter frame  104  such as a Kinze Row Unit. 
     A support frame  106  is secured to frame  104  and extends rearwardly to support wheels  108 . Ladder  110  extends upwardly to operator platform  111 . Operator seat  112  is positioned beside seed support rack  113 , in front of seed drop tubes  114  and console touch screen  116 . Operator console  116  provides the operator input and control of the programmable logic controller (“PLC”) housed in cabinet  118  and discussed in detail below. 
     Referring to FIGS. 2 and 3, metering unit  130  is mounted to frame  104  below frame  106 . Vacuum unit  140  is connected through vacuum line  142  to metering unit  130  to provide the vacuum for seed pick up, described below. Vacuum lines  144  provide a vacuum to seed discard jar  146  to collect discarded seeds from metering unit  130  through vacuum tube  148 . 
     Referring to FIG. 6, double disk openers  170  and dual gauge wheels  172  combine to form a clean V-formed seed trench  174  containing spaced-apart seeds  176  from seed tube  178 . Trailing closing wheels  180  firmly press the soil against the seeds. In FIG. 6, trailing closing wheels  180  are held above trench  174  in order to show the spacing of seeds  176 . 
     Referring to FIG. 7, check cable head  182  extends from the side of vacuum planter  100  and receives a check cable which is threaded through check cable head  182 . The check cable (not shown) has evenly spaced buttons. The first button is used to trigger initialization of the planting routine and calibration routines (described below) via an electronic switch  184 . The system monitors the buttons to update calibration settings while in the planting mode (described below). 
     An assembled metering unit  130  is shown in FIGS. 8 a  and  8   b,  while an exploded view of metering unit  130  is shown in FIGS. 9 a  and  9   b.  Referring to FIGS. 8-13, seed diverter  192  pivots about axis  194  in response to actuation of solenoid  198  pivotally secured to pins  196  in diverter block  192 . The lower surface  200  of diverter  192  is arc shaped with its radius of curvature extending from axis  194 . Seed tube  202  extends from the upper surface of seed diverter  192  through its lower arcuate surface  200 . Diverter plate  204 , shown in FIG. 14, includes an aperture  206  which is axially aligned with pivot pin  194  extending from seed diverter  192 . 
     The top half  210  of inner seed tube  212  and outer seed tube  214 , and the bottom half  230  of inner seed tube  232  and outer seed tube  234  are shown in FIGS. 15-22. When top half  210  and bottom half  230  are bolted together, inner and outer seed tubes are formed which keep the seed completely separate to avoid cross contamination of seeds. The bottom portion of seed tube halves  112  and  114  are angled inwardly along surfaces  116  and  118 , respectively, toward seed tube block  230 . When blocks  210  and  230  are assembled, surfaces  236  and  238  align with surfaces  216  and  218 , respectively, to form a sloping path to inner seed tube outlet  244  and outer seed tube outlet  246 , respectively. 
     The upper arcuate surfaces  220  and  240  of seed tube blocks  210  and  230 , respectively, have a radius of curvature which matches the radius of curvature of surface  200  of diverter block  192  shown in FIGS. 10-13. A cutout relief  312  on the rear face of block  230  provides a guide for singulator adjustment plate  310  described below in association with FIG.  38 . 
     Referring to FIG.  9  and FIGS. 23-26, inner  250  and outer  251  seed sumps are illustrated, each having an inner arcuate surface  252  to provide path for the seeds from seed apertures  244  and  246  to the seed plate  330 , discussed below. Inner  250  and outer  251  seed sumps include beveled surfaces  254  and  256 . Beveled surface  254  is held against seed plate  330  in the sump to hold the seeds against the seed plate  330 . Inner  250  and outer  251  sumps pivot about axis  258  in response to actuation of inner  259  and outer  261  seed dump solenoids. 
     The bottom half of seed tubes  230  is secured to cover plate  260  with inner  250  and outer  251  seed sumps extending through aperture  262  to engage seed plate  330  as shown in FIGS. 9 and 27. 
     Referring to FIGS.  9  and  28 - 31 , divider vane  270  is illustrated. Divider vane  270  is sandwiched between cover plate  260  and seed plate  330 . Divider vane  270  includes three vanes  272 ,  274  and  276  which present inner channel  278  and outer channel  280 . Channels  278  and  280  are spaced such that inner and outer seed sumps  250  and  251  fit between the respective vanes and against seed plate  330 . Divider vane  270  keeps the seeds separated at the plate to prevent cross contamination of the seeds. 
     Referring to FIGS. 32-38, inner seed singulator  290  and outer seed singulator  300  are illustrated. Inner seed singulator  290  and outer seed singulator  300  are adjustably mounted within inner divider vane channel  278  and outer divider vane channel  280 , respectively. Singulators  290  and  300  include ribs or vanes  292  and  302 , respectively, which singulate the seeds carried on seed plate  330  such that multiple seeds are not carried along these inner and outer rings on seed plate  330 . Singulator adjustment plate  310  is used to adjust singulators  290  and  300  as a pair. A single adjustment screw (not shown) moves the singulators in and out radially to seed plate  330 . 
     Referring to FIGS. 9 and 39, a pair of seed ejectors  320  are spaced along the inner and outer seed rings of plate  330  to ensure that the seed falls from the plate at the correct position. 
     Referring to FIGS. 9 and 40, a dual ring seed plate is illustrated having an axis of rotation about axis  332 , and having inner and outer ring of seed holes  334  and  336 , respectively. On the rear or vacuum side of seed plate  330 , seed holes  334  and  336  are countersunk as indicated by  338  and  340 , to increase the air flow through inner and outer holes  334  and  336  thus increasing the vacuum level. Plate  330  includes inner  342  and outer  344  agitation grooves to keep the seed held against the vacuum seed plate  330  agitated to improve the seed pick up of seed holes  334  and  336 . Seed plate  330  may be fabricated from a fabric/resin composite material which may be available from Orkot or any other rigid material able to be machined. Seed plate  330  rotates clockwise as planter  100  moves forward. 
     Referring to FIGS. 9,  41  and  42 , vacuum seal  350  is illustrated having an inner aperture  352  which is axially aligned with axis  332  of seed plate  330 . Vacuum seal  350  has inner channel  354  and outer channel  356  which provide a vacuum area for seed holes  334  and  336  on seed plate  330 . The vacuum applied to the back of plate  350  is transferred to the chambers through openings  358 ,  360 ,  362  and  364 . Aperture  352  accommodates vacuum seal  376  shown in FIG.  46 . Opening  362  in vacuum seal plate  3650  accommodates inner vacuum cutoff shoe  370  and opening  364  in vacuum seal plate  350  accommodates outer vacuum cutoff shoe  372  shown in FIGS. 43 and 44. 
     Vacuum cutoff shoes  370  and  372  are spring or biased to the back side of seed plate  330  and pulled off or disengaged from plate  330  upon actuation of inner solenoid  380  and outer solenoid  382  shown in FIG. 9, which are linked to inner shoe  370  and outer shoe  372  through connecting rods extending through apertures in vacuum housing plate  378 . Solenoids  380  and  382  are held in place with mounting block  384  secured to housing  378 . When vacuum cutoff shoes  370  and  372  are spring loaded to seed plate  330  they cutoff the vacuum to the respective set of seed holes  334  and  336  and prevent seed in the inner and outer sumps  250  and  251  from being picked up. When one of the shoes  370  or  372  is pulled from plate  330  by actuation of either solenoid  380  or  382 , respectively, the vacuum is allowed to reach holes  334  and  336  in seed plate  330  where seed in the inner  250  or outer  251  sump may be picked up. This permits staging of the seed against seed plate  330  so that it is readily available for the start of a plot. Additionally, this permits more accurate starts and stops to plots. 
     Referring to FIGS. 4 and 47 through  49 , control of the metering unit discussed above is accomplished using computer  150  housed in cabinet  118 . Fan  152  provides cooling air for computer  150 . Inputs and outputs to computer  150  are connected through wiring strips  153 , through relays  154 , to the signal conditioning and monitoring board  156  and I O board  900 . Input power from tractor  102  (FIG. 1) passes through transformers  58  to computer  150  and the solenoids discussed hereinabove. 
     Referring to FIG. 48, computer  150  consists of CPU  750 , input modules  752 , output module  754  and counter module  756 . In the preferred embodiment, computer  115  is an Allen-Bradley programmable logic controller (PLC) Model No. SLC5/03 (CPU  750 ). PLC  150  monitors and controls sensors, signals and solenoids through I/O interface board  900  and signal conditioning and monitoring board  156 . User inputs to PLC  150  are provided through touch screen  116  which displays information from PLC  150 . 
     Referring to FIG. 47, I/O interface board  900  acts as a series of switches between PLC modules  752 ,  754  and  756 , and the sensors, solenoids, other signals and power supplies. I/O board  900  reduces the possibility of noise affecting PLC  150 . Outputs  902  go high to 24 volts DC  904  when activated, and float low when in the off state. Each output  902  has its own transistor  908  (such as part No. 2N3904) that it uses to switch a 12-volt DC input signal  906  to its corresponding output device connected to one of outputs  902  to be turned on or off. Each input signal  906  passes through resistor  910  to the base of transistor  908 , which switches power from connector  904  to outputs  902 . Transistor  908  may be a PNP transistor or a JFET transistor. An electrical schematic of the signal conditioning and monitoring board  156  is shown in FIG.  49 . Variable voltage regulators  800  (such as part No. LM317) are wired using resistors  802  to convert the 24-volt DC input from power supply  158  to an 8-volt DC regulated output  803 . Output  803  supplies clean, noise-free power to the seed sensors. Each voltage regulator  800  includes a heat sink in order to supply enough current without overheating. 
     Fixed 12-volt DC regulators  804  supply clean, noise-free power to all of the chips on board  156 , and provide the reference value for the low-voltage alarm. 
     OP-amps  806  and  808  are configured as comparators for the power supply voltage alarm. Each amplifier  806  and  808  has one input tied directly to the input supply voltage  158  which is the signal being tested. The low voltage reference is the clean 12-volt DC output from voltage regulators  804 . The high-voltage for OP amp  806  is set by potentiometer  810 . If the supply voltage  158  rises above the high threshold, the output from OP amp  806  will immediately turn on NPN transistor  812  which switches the 24-volt DC input from supply  158  to the corresponding PLC input which is in turn detected by the PLC software, which displays the appropriate error message and sounds an alarm as discussed in detail below. If supply voltage  158  drops below the low threshold, OP amp  808  turns on NPN transistor  814  which switches 24 volt DC power from supply  158  to the appropriate PLC input. In response, the PLC software displays the appropriate low-voltage error message, and activates an alarm, as discussed in detail below. 
     Seed sensor input signals  820  are each pulled up to 12 volts DC by 100K resistors  830  when in the off state. Depending on the strength of the signal received from the seed sensor, the corresponding output from the sensor (input  820  to board  156 ) is pulled low. Signals  820  are then input to a  339  quad OP-amp comparator  832 . Each input signal  820  is compared to a threshold value when a signal  820  drops below the threshold, the corresponding output from OP amp  832  switches the corresponding transistor  840  on, which transmits the signal to the input of corresponding timer  850 . Timers  850  (such as part No. NE555) are all configured as mono stable multi vibrators (one-shots). Timers  850  produce an output pulse of consistent time duration regardless of the length of the input trigger pulse. The outputs from one shot timers  850  turn on and off their corresponding transistor which sends a 20 volt DC signal to the corresponding PLC input module. The sensitivity of the seed sensors can be adjusted by changing the threshold voltage at the input to the comparator  832 . Since the seed sensors are sinking sensors, raising the threshold increases sensitivity and lowering the threshold decreases sensitivity. Timers  850  ensure the each seed signal pulse is long enough to be detected and counted by the PLC program. 
     Referring to FIGS. 50-60, upon initialization or start up of PLC  150  (FIG.  4 ), the PLC software begins execution as illustrated by block  500 . Execution is delayed for a predetermined period of time to allow the sensors and power supplies to stabilize  502 . If the sensors and power supplies are not correctly initialized  504  the system reboots  506  and returns to start  500 . If the system is correctly initialized  504 , the main menu  508  is displayed on touch screen  118  and provides the operator with a choice  510  of display options. 
     If the operator selects solenoid sensor check  512 , the sensor and solenoid check screen is displayed with touch buttons for each solenoid on the planter. All solenoids may be released by selecting button  514 . Individual solenoids may be energized by selecting the solenoid button such as fire diverter  516 , fire outside sump solenoid  518 , fire inner sump solenoid  520 , fire outer vacuum shoe  522 , and fire inner vacuum shoe solenoid  524 . Touch screen  118  displays the current state for each solenoid. 
     Similarly, the state of the solenoids may be toggled to the relaxed state by selecting diverter solenoid  526 , outer sump solenoid  528 , inner sump solenoid  530 , outer vacuum shoe solenoid  532 , or inner vacuum shoe solenoid  534 . If the state of a solenoid fails to change as indicated on touch screen  118  after toggling a solenoid between the energized and relaxed states, either the associated position sensor for the solenoid has failed, the solenoid itself has failed or there is an obstruction preventing the solenoid from moving between states. The sensor and solenoid check  512  is primarily a diagnostic mode of operation that may be used to determine if any of the solenoids or sensors are not operating properly. The operator selects exit  536  to return to main menu  538 . 
     From the main menu as shown in FIG. 50, the operator may select upload plot numbers  540 . When this option is selected, the program goes into a “ready to receive” mode  542  so that the operator may input their own plot numbers via as RS 232 cable to be stored with the collected data. The plot numbers file may be a comma-delimited ascii text file with plot numbers. The program will continue to receive plot numbers  544  until an end of file character  546  is received. When the end of file is received, the program stores the input strings entered by the operator and returns to the main menu  538 . If the operator does not enter his or her own plot numbers, a standard set of range and row numbers starting with row one, range one and increasing from that point are used. 
     If the operator selects download stored data  548 , the program initializes the COM port to send data  550 . The first plot of data is converted to ASCII format  552  and sent out through an RS 232 COM port  554 . If an end of file has not been sent  556 , the register is moved to the next plot address  558  and converted to ASCII format  552 . The next plot of data is sent  554  and then checked for end of file  556 . If an end of file has been sent to indicate the end of the plot data, the program returns to the main menu  538 . Once all the data has been sent, the storage addresses in the PLC are reset so that the maximum amount of data storage space is available for the next run. The RS 232 port is a standard configuration DB9 connector. 
     From the main menu  508 , the operator may choose  510  to change the set up  560 . Various user options are displayed  562  such as to send data as taken  564  which sets up the RS 232 COM port and sets a flag in the program to send data for each plot  566  at the end of each plot. In the preferred embodiment, the number of rows to be simultaneously planted may be set  568  between one and four rows. However, it should be appreciated that a planter  100  may be configured to plant more than four rows at a time. Planter  100 , as shown in FIG. 1, is set up to plant two rows simultaneously. The power sensitivity check may be set  570  to low, medium, high or off  572 . This allows transients caused by actuation of the solenoids to be ignored. The actuation or pull time for each solenoid  574  may be set to allow additional time for the solenoids to actuate before an error is indicated to the operator. This is useful when a solenoid is weak. After the options have been set  562 , the operator may return to the main menu  538 . 
     From the main menu  508  the operator may choose  510  to calibrate the system  576 . Calibration is necessary only when the planter is used for the first time for the day, although it may be used anytime the user feels that it is necessary. When calibration is selected  576  the operator enters the button spacings and the cells per ring  578  corresponding to the distance between buttons  800  on cable trip wire  802  shown in FIG.  61  and the ring of seed holes  334  shown in FIG.  40 . When the system is ready to calibrate  580 , the encoder counts are cleared when the first button is detected and the button count is set to one  582 . The calibration procedure compares the pulses coming from a rotary encoder being driven off of a wheel contacting the ground and rolling during normal operation, to a known position according to the distance between buttons on the cable trip wire and calculates a correction factor that gives the correct position of the planter at any point using the encoder pulses. The calibration procedure monitors and counts the encoder pulses and waits to receive a check head signal  584  from switch  184  on check head  180 . 
     When the cell counting encoder has rotated 220°  586 , the distance count is stored as the uncalibrated plate load distance  588 . The plate load distance is the distance traveled between the position where the vacuum is allowed to the plate  330  and seeds are picked up, to the position where the plate  330  has rotated around and the seeds are dropped off and planted in the soil. When the next button is reached  590 , the button count is incremented  592  and the distance for button two is captured  594 . A temporary calibration factor is set  596  based on the encoder counts between the first and second buttons. 
     Next, the program checks to see if the button count is greater than or equal to three  598 . If it is not, the program flow returns to monitor the encoder counts and the check head signal  584  and the loop repeats. Once the button count is greater than or equal to three  598 , the temporary calibration factor is compared to the calibration factor calculated between button one and the last button  600 . If the difference between the temporary calibration factor and the overall calibration factor is not within 0.5%  602 , then another set of encoder data is collected and the loop is repeated. Once the temporary calibration factor from the last button counted is within 0.5% of the overall calibration factor, the calibration is complete  604  and the calibration factor and load plate distance is stored  606 . The load plate distance is calculated by using the input pulses from two encoders. One encoder is turning at a rate proportional to the drive wheel, or ground travel, and the other is turning at a rate proportional to the seed plate  330  rotation on the seed metering units  130 . When these calibration factors are successfully calculated, the user may go back to the main menu  538 . 
     From main menu  508  the operator may choose  510  to start planting  508 . The system first checks to determine if the system is calibrated  610 . If the system is not calibrated, processing returns to the main menu  500 . If the system is calibrated, the operator is presented with several screens to input all the factors necessary to plant the desired plots  612 . The operator will enter the plot length  804 , which is the distance between the first seed in the plot and the last seed in the plot. Next the user will enter the alley length  806 , which is the distance between plots where no seed are planted, or a “dead space” in the field to separate adjacent plots. Next the button spacing  808  of the check cable  802 , if one is being used is input. Next the number of cells or holes per ring on the seed plate  330  are entered. At this point, the operator may choose to start where he or she left off with current range and row numbers, or the operator may clear out the data storage addresses and reset the plot identification numbers. Finally the operator enters the number of plots  803  that are in each trip down the field. Given this information, the number of buttons  800  on check cable  802  that are necessary to properly plant the field is displayed. When all information is entered, a screen is displayed showing the seed counts per row, plot identification number, time taken to plant the plot, and the number of seed holes that went around on each seed plate during the plot which corresponds to the number of seeds planted. If all the values are displayed correctly  614  the operator may select plant mode  616 . 
     In plant mode  616  after loading the check head cable  802  into the check head  180  at the beginning of each pass down the field, the operator selects reset button  618 . Reset button screen  618  also displays whether the planter is on the baseline side of the field  810  or the far side of the field  812 . When reset button  618  is pressed, the diverter solenoid  198  is energized to move diverter  192  and align diverter seed tube  202  with outer seed tube  234  in seed tube block  230  and outer seed sump  251  as shown in FIG.  62 . Inner and outer vacuum shoe solenoids  380  and  382  are de-energized so that inner and outer vacuum shoes  370  and  372  are pressed against plate  330  to cutoff the vacuum to the inner  334  and outer  336  seed rings within inner  250  and outer  251  seed sumps. Additionally, inner seed sump solenoid  259  and outer seed sump solenoid  261  are de-energized to close seed sumps  250  and  251 , respectively. The position of each solenoid is displayed for the operator. If each solenoid is in their correct position, the operator may dump the first packet or lot of seed  814  into the unit and begin to pull the planter forward. 
     At the baseline side of the field  810 , when the first check ball  800  trips check ball switch  184  and the operator has indicated that planting will start at the baseline  624 , the system begins monitoring the position of the planter via the encoder  628 . Once the plot start position  630  is reached solenoid  382  is energized to open outer vacuum cutoff shoe  372  and seeds  814  are picked up by outer seed holes  336  in seed plate  330 . The plot start position is the base line position  810  minus the plate load distance determined in the calibration cycle. 
     When the computer determines that the planter is at the base position  810 , diverter solenoid  198  is energized to toggle diverter  192  to the inner row position and align seed tube  202  with inner seed tube  232  of seed tube block  230  and inner sump  250 . A dump buzzer or other indicator alerts the operator to dump the next seed lot  816  into the unit. See FIG.  63 . 
     The planter&#39;s position is monitored  634  until the planter reaches the base line which is the plot start plus the plate load  636 . Once the base line  810  is reached, the unit begins counting seeds and cells  638 . The system monitors the position  640  of the planter based on the encoder pulses and the calibration factor. When the end of plot is reached  642 , outer sump  251  is opened  644  and any remaining seeds in sump  251  are dumped and vacuumed into discard jar  146 . See FIGS. 64 and 65. Once all seeds are singulated  650 , at the position on seed plate  330  where the last seed hole is clear of the area covered by outer vacuum cutoff shoe  372 , the outer vacuum cutoff shoe is closed. Additionally, at the position where the last seed  814  is passed the point on seed plate  330  where all seeds are singulated, sump  251  is closed  652 . 
     Once the distance for sump cleanout and plate load  654  has been traveled by planter  100 , the unit stops counting and stores the data for this plot or sends the data out on the RS 232 if required  656 . 
     If this is not the end of the pass  658 , the system monitors the planter position  660  to determine the start of the next plot  662 . Once the next plot start has been reached, the inner vacuum cutoff shoe  370  is opened and seeds  816  are picked up on the inner ring of seed holes  334 . At the same time, diverter  192  toggles back to pointing to the outer row of seed holes  336  and the dump buzzer is sounded to alert the operator to dump the next seed lot  814  into the unit. See FIG.  66 . 
     Finally, the plot number is increased or incremented  664 . The planter position is monitored  666  to determine the start of the next plot  668 . The unit starts counting for the inner seed ring for plot  2  when the outer seed ring  336  has dropped the last seed  814 . Once the plot start plus plate load position  668  has been reached, the unit begins counting seeds  670  for the inner seed ring  334 . The planter position is monitored  672  until the end of plot is reached  674 . At this point, inner seed sump  250  is opened  676  to clean out the sump as shown in FIG.  67 . Any remaining seeds in the sump are ejected into discard jar  146 . At the position on seed plate  330  where the last seed hole  334  is clear of the area covered by the inner vacuum cutoff shoe  370 , inner vacuum cutoff shoe  370  is closed. At the distance where the last seed hole  334  on seed plate  330  is past the point where all seeds are singulated  680 , inner seed sump  250  is closed  682 . 
     The planter position is continued to be monitored  678  to determine the end of the next plot as calculated by the cleanout and plate load distance  684  on seed plate  330 . Once the end of plot has been reached, the unit stops counting and stores the data or sends the data out on the RS 232 if required  686 . If this is not the end of the pass  688 , the system continues monitoring the position of the planter  690  to determine the plot start  692 . When the plot start minus the plate load distance has been reached  692 , the outer vacuum shoe  372  is opened and seeds are picked up on the outer ring of seed holes  336 . At the same time, the diverter  192  toggles back to pointing to the inner row of seed holes  334  and the dump buzzer is sounded to alert the operator to dump the next seed lot  618  into the unit. Finally the plot number is incremented  694 . This process is repeated  696  down the field to plant each plot  803  and leaves the correct alley  806  between successive plots. As each plot is planted, the plot time is recorded and displayed, the number of seeds that passed through the sump is displayed and recorded, and the actual number of seeds in each row is displayed and recorded. The seeds for each plot are counted from the position where the first seed picked up reaches the drop off point to the point where the last seed reaches the drop off point plus an amount of time for the seed to fall past the seed sensor. 
     In the planting mode, error-checking process  706  runs in the background. The PLC compares the state of individual outputs that control solenoid positions to the inputs coming from sensors on the row units showing the actual position of the solenoid. When a disagreement occurs, or error condition is detected  708 , an alarm buzzer is sounded  710  and the precise location and nature of the error is displayed to the operator. At this point the user has the option to acknowledge the alarm  712  which resets the enable bit for this condition and disables the alarm  714 . Additionally, the user may acknowledge all alarms  716  and clear all error conditions  718 . 
     The vacuum level at each metering unit is also monitored, as is the input power supply voltage. This air checking function is disabled  704  and  698  in FIGS. 57 and 58, such as at the end of the field when the tractor may be idled down and the planter is being turned around  702 . This is to prevent nuisance error reporting. 
     Additionally, another background process to monitor the planter position  720  monitors check head signal  722  to calculate the planter&#39;s actual position or location  724  by the button  800  count and button spacing  808  on cable  802 . The planter&#39;s actual position is compared to the calculated encoder position  726  and a position correction factor is calculated along with a new calibration factor  728 . In this way, the current position is corrected every time a known position is reached to keep the accuracy high. 
     When the return trip at the far side  812  of the field is started, the PLC calculates an offset. This offset is to account for the possibility that the known position indicator will not be in the correct position to start the first plot. By adding the offset, the planter is able to place the first seed of the return pass down the field even with the last seed from the previous pass. This also ensures that the alleys line up across the field when all plots are planted.