Plc registers pdf

The timer retains a count of 6. Timing has not reached the preset value of 14 seconds, and the timer output is still off. The timer does not reset unless INO02 is opened. Format b in figure is an alternate. When the timer goes on, its output 31 internal turns output 78 on. In some PLC formats, the register count is not displayable.

Figure c illustrates'a special case when the enable and reset are two separate in- puts rather than a. This configuration can be used for special program requirements when the arrangement is available. Their functions are shown in figure e and f. A system of X for on and O for off is normally used.

The examples illustrate this convention. In some systems a 1 is used instead of an x to indicate contact closed. Output B comes on at a specific set time after Outpa turned on. When A is turned off, B also goes off. When A is turned off, B remains on fora sri time period before going off. A and B go on at the same time. B goes of specific set time period, but A remains on. Example Repeat cycling. An output pulses on and quickly off at a con preset time interval.

Output B will run for its specified time interval a A is turned off during the B timing interval. Example Alternate on and off of two outputs. An example of this timing agi cation is two alternately flashing signal lights. The time on foreach the two lights may be the same, or the two times could be st different intervals, Example Multiple on delay.

Two different events start at different time inte after an initial starting time reference point. Example Multiple off delay. Two different functions remain on for two dif time intervals after a process is turned off. Example Interval time within a cycle.

We may Tequire that an output come seconds after system startup, remain on for 4. The interval would then be repeated only afte system is shut off and then turned back on, There are other timin, 8 examples we could illustrate as well; however, thes i 7 Pi of PLC timing capabilities.

In most cases, Problem. Each example includes a dit! A motor and its lubrication PUMP moto, both running. Lubrication for main motor bearings is required during motor coas, After the main motor is shut off, the lubricating pump remains on for a time corespon, to coaSt-down time.

In this example, a lubricating pump remains on for 20 seconds afer, main system is shut down. Figure shows the required program.

Example is for a wood sawing operation. The sawing operation takes 4. After the sawing takes place, a blower to blow away the sawdust is to keep run- ning until the operation is tuned off. Figure shows a program for this where both the saw, Output A, and the blower, Output B, go on at the same time.

The saw, Output B, goes off after 4. Example is for a package dual stamping operation. Figure shows a pro- gram for this where stamping times of 8 and 14 seconds are required. The end is stamped for 8 seconds, output M, and the top for 14 seconds, output N. In a paper mill, as finished paper comes out of apart machine to the finished roll, a roll number is to be printed on one edge at intervals.

The timer then after one scan immediately shuts itself off through the opening of a normally closed contact in the timer enable line, Once TO13 goes off it resets the enable contact to closed and the 12 second timing cycle is repeated. An alarm is to sound for 17 seconds after a machine is started to alert personnel in the area that the machine has been started. The alarm goes on when the machine is started. The alarm stays on for 17 seconds, even if the input is turned off during the second timing period.

The machine could be coasting down. INOO11 must be opened to reset the system, EXAMPLE 14 The Sixth example is an alternating two output system shown in Figure , For example you have a warming light system on a machine to indicate itis running, A single light on-or a single flashing light is not deemed sufficient.

You want two alternating lights. Outputs CR11 and CR12 control the two red lights. To change the times to other equal or nonequal times, reset the C. The second time delay is accomplished by adding 5 seco" Hist 7 seconds, for a resulting time delay of 12 seconds. Multiple time delay 0 secomplished by appropriately adding more timers - Multip! Close INOO! Hydraulic pres » Presses in and stays in the Pressed position.

Tra59 T Hl Ov. Finally, a third press actuator C, CRO19, comes in from a third direction and holds position. Opening INOO1 release all three presses so the part may be removed, For three or more time delays, contirtue to use more cascaded additional timer functions. Alternatively, there can be separate a on inable inal Reset, de i!

Conventional counters, mark fee ry j S r counter fag include mechanical, electrical, and electronic types. Others contain ii high-speed counters for high-frequency counting capability.

The up counter counts fe, O up toa preset count, where some indicating action takes place. The down counter sq from the preset number and counts down to 0, where the indicating action takes plagy. Figure Ial is one format, the block format, and is the one ye use in the chapter.

The count at which the counter output is to go on is entered into the preset space. The count can be a constant as shown, 21, or can be a register Which has a varying value from the process. For the up counter, the count starts at 0 and increments by ead time INOO1 is pulsed on. When the preset value is reached, the output, CR17 in our example, goes on, As the count goes on beyond the preset value, the output stays on.

Opening INO at any time resets the counter to 0. The down counter operates in a similar manner. The cout starts at the preset value and increments down by one each time the input INOOI goes ot When the count reaches 0, the output goes on. Figure shows a coil format found in some PLC models. The counter out is internal logic. The counter, 32 in our example, counts to 21 and turns on.

The preset can be set to a value as shown or can be set at maximum count if you only wish to observe the net count in the designated regis HR One precaution when using this function is to know whether the function Wil accept negative numbers in case the net count goes negative. Some PLCs contain a high-speed counter, as shown in figure c, Refer to the PLC Sperating manuals for the frequencies at which their high-speed counter operates number of auxiliary functions work with these counters.

Again, see the PLC manvals the system setup, , Tn some applications, you may wish to stop the count for a time without it rset"? Allen-Bradley up-counter function along with a functional timing diagram.

The Allen-Bradley down-counter function is similar. The fist is for a basic application for counting events. The second and third examples use more than one counter for process control counts. The fourth through sixth examples use the counter function in conjunction with the timer function, which was described in chapter 9. Example Straight counting in a process.

The counter output goes on after the Set count is received by repetitive pulses to the counter input. Example Two counters used with a common register to give the sum of two counts. Example Two counters used with a common register to give the difference between two counts. Example A process where a timed interval is started when a count reaches a preset value. Example A process where a count of events is to start after a fixed time interval.

After a certain number of counts 41 occurs, the output goes on. The output can be used to energize an indicator. The output status could also be utilized in the ladder diagram logic in the form of a contact. The counter function is shown for either an up counter or a down counter.

They both perform the same function in this illustration, Either counter will function if its enable line is energized. I off to reset the system. Each proximity device feeds information into its own counter Fimcton. Tey count is kept in a holding register common to both counters. An accurate initial count is needed.

This count number is programme ina! It is normally necessary to put this count number in he te! Similarly, the parts leaving decrease the common ry count through the down counter. The number value in register HR1O1 represents the! We are assuming that no parts falloff the conveyer sniys, are added along the way.

The up counter preset value is irrelevant in this application. It does nt nat whether the counter outputs are on or off. The output on-off logic is not used. The operation is the same as for figure da. EXAMPLE This example is for a timed process that occurs after a certain process count is real After a count of 15 from a sensor, a paint spray is to run for 25 seconds.

Figure has a program that accomplishes the count and time operation. INoo7 ee 00! Comes on after counts as inputed by INoo2 slanting after 1 hour. In this process alter the process starts. A timer output contact criod. The closure then enables,the counter to Start counting input pulses. After a count of , the output comes on. How many parts per minute are going past a certain process point? This example addresses this problem. The timer and counter are enabled at the same time, The counter is pulsed foreach, going past its sensor, which is connected to INO The counting begins and the jn.

Pulses continue but do not affect the PLC counter. The pa. After INGO it eclosed, the process starts over. Explain the programming, operation, and utilization of the repetitive clock.

Describe the various PLC trigonometric and log functions. Describe other major PLC arithmetic functions. Apply arithmetic functions to process control operations.

Arithmetic functions are sometimes deg, ag math fumetions, These basic functions—ADD. A progr for performing functions and others. For figure, The addition will not take place cot! The resulting value then appears in the specified destin register. In many PLCs, operand 2 can be number or the value in a designated register, Figure Ib shows another format that operates similarly.

The two numbers tobe added are entered in locations 30 and 31 The result of the addition then appears in location 32 when the input is energized. Figure 1I-le shows another format found on some ae ca ou ean add more than two numbers using one function.

For exam If you add plus , the sum, which « the coil will not come on, The sum, , other hand, the sum of plus is In this case, the destination register will Note that we are using functions also work for binary me PLCs its status is irrelevant. In other register overflow or negative value. For ing number exceeds the register counting ple, assume the decimal register limit is quals , is within the register limit, and will appear in the destination register.

On the The arithmetic numbers and other numbering systems. You may choose any numbering system, depending on the requirements of your particular PLC model. Figure illustrates the ADD function for two examples. One example is for a result less than , and the other is for a result greater than For some reason We cannot get to the main Cony a make a count. The main conveyor count is determined from the count of parts wy from the other two conveyors.

The count on each feeder-conveyor is deter ny counter not shown. The counters on each feeder-conveyor are input-pulsed by gp ty detector once for each part leaving the conveyors. The count of total parts entering in conveyor is then determined by adding the two feeder conveyor counts using 8 the 4 ery function. For illustration, we monitor the total count every 30 seconds. The in dy ADD function is pulsed on and immediately off by pulsing the ADD function ena count could be printed out as shown in figure every 30 seconds, Th Note that this addition method is an alternate solution to a similar problem, indy, ter 10 using counters and a common register.

For subtraction, operand 2 is subtracted from operand 1. The result is found, the destination register. For subtraction, we discuss the block formats only. In some PLCs the direct answer yy appear. In other PLCs, the coil status is significant for complete answer description. Thea on-off operation for subtraction differ from that of addition. When the result is positive, ty coil is off and the result is found in the destination register.

When the result is nega, the coil is on and the resulting negative number value is found in the destination register. Itis simi, addition example.

In this example, the output count and only one input count are ava One of the conveyor inputs is not accessible for some reason. To obtain the input coy subtract the input B count value from the output count. The result is the A conveyor coun count is again determined by a second counting interval.

The count is taken for 30 sex used, and then reset to zero. The PLC can easily and quickly reset the dimensog and tolerances. The preset dimensional values are transmitted to two specified PLC oy, puts. These output values are used to set the positions of an automatic gauging sYstem, In the example, the base dimension, or set point, is set at 6. Figure illustrates how the settings can be accomplished by programming , PLC. For three eternally fixed values, a PLC is not needed.

Our system is valuable wher the dimensions are varying quickly as production varies. The set point is entered ini Feeder. HRO receives the upper tolerance value, and HR receives the lower tolerance value. When the circuit in figure is enabled, the upper and lower limits are calculated.

For figure! For figure c, we show. If the number in location is equal to , output is energized, ; Figure shows three basic comparison function layouts. The two numbers being compared are operand 1 and operand 2. Human Resources Skills. Health Care Skills. Finance Skills. All Courses. All Practice Tests. Job Recommendation Latest. Jobs in Meghalaya Jobs in Shillong.

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