Chapter 9 - AutomationDirect
Contents
1. Use arrow keys to select point then use Y2 is now on ON and OFF to change the status c c SHFT ie Y 10 YO DLO06 Micro PLC User Manual 3rd Edition Rev C 9 9 Chapter 9 Maintenance and Troubleshooting E Noise Troubleshooting Electrical Noise Problems Noise is one of the most difficult problems to diagnose Electrical noise can enter a system in many different ways and falls into one of two categories conducted or radiated It may be difficult to determine how the noise is entering the system but the corrective actions for either of the types of noise problems are similar Conducted noise is when the electrical interference is introduced into the system by way of an attached wire panel connection etc It may enter through an I O circuit a power supply connection the communication ground connection or the chassis ground connection Radiated noise is when the electrical interference is introduced into the system without a direct electrical connection much in the same manner as radio waves Reducing Electrical Noise While electrical noise cannot be eliminated it can be reduced to a level that will not affect the system Most noise problems result from improper grounding of the system A good earth ground c2. YO force from programmer YO in image register YO at output module DLO06 Micro PLC User Manual 3rd Edition Rev C G 17 EJ Chapter 9 Maintenance and Troubleshooting B The following diagrams show a brief example of how you could use the DL06 Handheld Programmer to force an I O point Remember if you are using the Bit Override feature the CPU will retain the forced value until you disable the Bit Override or until you remove the force The XO YO OUT image register will not be updated with the status from the input module Also the solution from the application en program will not be used to update the output image register The example assumes you have already placed the CPU into Run Mode From a clear display use the following keystrokes STAT ENT 16P STATUS BIT REF X Use the PREV or NEXT keys to select the Y data type Once the Y appears press 0 to start at YO next ENT Use arrow keys to select point then use ON and OFF to change the status Y2 is now on ON c c SHFT INS Regular Forcing with Direct Access From a clear display use the following keystrokes to force Y10 ON Solid fill indicates p
3. The I O point status indicators are logic side indicators This means the LED which indicates the on or off status reflects the status of the point with respect to the CPU On an output point the status indicators could be operating normally while the actual output device transistor triac etc could be damaged With an input point if the indicator LED is on the input circuitry is probably operating properly Verify the LED goes off when the input signal is removed Leakage current can be a problem when connecting field devices to an I O point False input signals can be generated when the leakage current of an output device is great enough to turn on the connected input device To correct this install a resistor in parallel with the input or output of the circuit The value of this resistor will depend on the amount of leakage current and the voltage applied but usually a 10K to 20K resistor will work Verify the wattage rating of the resistor is correct for your application Because of the removable terminal blocks on the DLO6 the easiest method to determine if an I O circuit has failed is to replace the unit if you have a spare However if you suspect a field device is defective that device may cause the same failure in the replacement PLC as well As a point of caution you may want to check devices or power supplies connected to the failed I O circuit before replacing the unit with a spare 9 8 DL06 Micro PLC User Manual 3rd Edition
4. Programmer key sequence results in an error or an illegal request Error Code Description Error Code Description E003 Software time out E526 Unit is offline E004 Invalid instruction RAM parity error in the CPU E527 Unit is online E104 Write failed E528 CPU mode E151 Invalid command E540 CPU locked E311 Communications error 1 E541 Wrong password E312 Communications error 2 E542 Password reset E313 Communications error 3 E601 Memory full E316 Communications error 6 E602 Instruction missing E320 Time out E604 Reference missing E321 Communications error E620 Out of memory E360 HP Peripheral port time out E621 EEPROM Memory not blank E501 Bad entry E622 No Handheld Programmer EEPROM E502 Bad address E624 V memory only E503 Bad command E625 Program only E504 Bad reference value E627 Bad write operation E505 Invalid instruction E628 Memory type error should be EEPROM E506 Invalid operation E640 Mis compare E520 Bad operation CPU in Run E650 Handheld Programmer system error E521 Bad operation CPU in Test Run E651 Handheld Programmer ROM error E523 Bad operation CPU in Test Program E652 Handheld Programmer RAM error E524 Bad operation CPU in Program E525 Mode Switch not in Term position Q H DL06 Micro PLC User Manual 3rd Edition Rev C Chapter 9 Maintenance and Troubleshooting EEEEIEGIGIMEGIGIGLGOSObGLLGZOSCRILGERILSBSOLELLAIRLLQN QILER IQ LLL
5. a personal computer refer to the DirectSOFT programming user manual It includes a troubleshooting section that can help you diagnose PC problems in communications port setup address or interrupt conflicts etc DLO06 Micro PLC User Manual 3rd Edition Rev C 9 7 Chapter 9 Maintenance and Troubleshooting E 1 0 Point Troubleshooting Possible Causes If you suspect an I O error there are several things that could be causing the problem High Speed I O configuration error A blown fuse in your machine or panel the DLOG does not have internal I O fuses A loose terminal block The auxiliary 24 VDC supply has failed The Input or Output Circuit has failed Some Quick Steps When troubleshooting the DL06 Micro PLCs please be aware of the following facts which may assist you in quickly correcting an I O problem HSIO configuration errors are commonly mistaken for I O point failure during program development If the I O point in question is in XO X2 or YO Y1 check all parameter locations listed in Chapter 3 that apply to the HSIO mode you have selected The output circuits cannot detect shorted or open output points If you suspect one or more faulty points measure the voltage drop from the common to the suspect point Remember when using a Digital Volt Meter leakage current from an output device such as a triac or a transistor must be Zz considered A point which is off may appear to be on if no load is connected the point
6. of personal injury or damage to equipment There are some important operational changes during Run Time Edits 1 If there is a syntax error in the new instruction the CPU will not enter the Run Mode 2 If you delete an output coil reference and the output was on at the time the output will remain on until it is forced off with a programming device 3 Input point changes are not acknowledged during Run Time Edits so if you re using a high speed operation and a critical input comes on the CPU may not see the change Not all instructions can be edited during a Run Time Edit session The following list shows the instructions that can be edited Mnemonic Description Mnemonic Description Timer Fast timer Or greater than or equal or less than Comparative Boolean Accumulating timer Load data constant Accumulating fast timer Load data double constant Counter Add data double constant Up Down counter Subtract data double constant Stage counter Multiply constant Store Store not Boolean Divide constant And And not Boolean Compare accumulator constant Or Or not Boolean And accumulator constant STRE STRNE Store equal Store not equal Or accumulator constant ANDE ANDNE And equal And not equal Exclusive or accumulator constant ORE ORNE Or equal Or not equal Load discr
7. 15 Chapter 9 Maintenance and Troubleshooting Forcing I O Points There are many times especially during machine startup and troubleshooting that you need the capability to force an I O point to be either on or off Before you use a programming device to force any data type it is important to understand how the DL06 CPUs process the forcing requests WARNING Only authorized personnel fully familiar with all aspects of the application should make changes to the program Make sure you thoroughly consider the impact of any changes to minimize the risk of personal injury or damage to equipment There are two types of forcing available with the DLO06 CPUs Chapter 3 provides a detailed description of how the CPU processes each type of forcing request Regular Forcing This type of forcing can temporarily change the status of a discrete bit For example you may want to force an input on even though it is really off This allows you to change the point status that was stored in the image register This value will be valid until the image register location is written to during the next scan This is primarily useful during testing situations when you need to force a bit on to trigger another event Bit Override Bit override can be enabled on a point by point basis by using AUX 59 from the Handheld Programmer or by a menu option in DirectSOFT You can use Bit Override with X Y C T CT and S data types Bit override basically NJ disa
8. LRGRSRIEERQR LECOLGBeOCDO COOOLBb G LLLLULLLLUPGELLALLLLULILOLLLEALLLULLLLCOU LoULLLLLELUHEULLLAIETLOOGLOEAO Program Error Codes The following table lists program syntax and runtime error codes Error detection occurs during a Program to Run mode transition or when you use AUX 21 Check Program The CPU will also turn on SP52 and store the error code in V7755 Appendix B provides a more complete description of the error codes Error Code Description Error Code Description E4 No Program in CPU E438 Invalid IRT address E401 Missing END statement E440 Invalid Data Address E402 Missing LBL E441 ACON NCON E403 Missing RET E451 Bad MLS MLR E404 Missing FOR E453 Missing T C E405 Missing NEXT E454 Bad TMRA E406 Missing IRT E455 Bad CNT E412 SBR LBL gt 64 E456 Bad SR E421 Duplicate Stage reference E461 Stack Overflow E422 Duplicate SBR LBL reference E462 Stack Underflow E423 Nested Loop E463 Logic Error E431 Invalid ISG SG address E464 Missing Circuit E433 Invalid ISG SG address E471 Duplicate Coil reference E434 Invalid RTC E472 Duplicate TMR reference E435 Invalid RT E473 Duplicate CNT reference E436 Invalid INT address E499 Print Instruction E437 Invalid IRTC DL06 Micro PLC User Manual 3rd Edition Rev C 9 5 Chapter 9 Maintenance and Troubleshooting B CPU Indicators The DL06 Micro PLCs have indicators on the front to help you determine potential pro
9. MAINTENANCE AND TROUBLESHOOTING In This Chapter Hardware System Maintenance v ae qo do a C oe am ee ac ea 9 2 DIGQNOSUCS acceded cece okk4 e xx re REGI RExEE ERE EXE RE EE 9 2 C PE TIBBICdEDES a a ph ok eor dod Ro oed eRe hate eho 9 6 Communications Problems scars er yr RR RR REUS 9 7 I O Point Troubleshooting o j0 054 404 ck a oe he oe Y Ro eer 9 8 Noise Troubleshooting xe edie Khe RR se 9 10 Machine Startup and Program Troubleshooting 9 11 Chapter 9 Maintenance and Troubleshooting E Hardware System Maintenance Standard Maintenance No regular or preventative maintenance is required for this product there are no internal batteries however a routine maintenance check about every one or two months of your PLC and control system is good practice and should include the following items Air Temperature Monitor the air temperature in the control cabinet so the operating temperature range of any component is not exceeded Air Filter If the control cabinet has an air filter clean or replace it periodically as required Fuses or breakers Verify that all fuses and breakers are intact Cleaning the Unit Check that all air vents are clear If the exterior case needs cleaning disconnect the input power and carefully wipe the case using a damp cloth Do not let water enter the case through the air vents and do not use strong detergents because this may discolor the case D
10. Rev C Chapter 9 Maintenance and Troubleshooting I Output points can be set on or off in the DLO6 series CPUs If you want to do an I O check out independent of the application program follow the procedure below Action Use a handheld programmer or DirectSOFT to communicate online to the PLC Change to Program Mode Go to address 0 Insert an END statement at address 0 This will cause program execution to occur only at address 0 and prevent the application program from turning the 1 0 points on or off Change to Run Mode Use the programming device to set turn on or off the points you wish to test When you finish testing 1 0 points delete the END statement at address 0 operation that can result in a risk of personal injury or equipment damage Make sure you have 1 WARNING Depending on your application forcing 1 0 points may cause unpredictable machine taken all appropriate safety precautions prior to testing any 1 0 points Handheld Programmer Keystrokes Used to Test an Output Point END EN XO X2 Ao a CS Insert an END statement 9 1 1 Ms at the beginning of the X1 X3 X4 program This disables VA the remainder of the program GD From a clear display use the following keystrokes 16P STATUS STAT ENT BIT REF X Use the PREV or NEXT keys to select the Y data type Y10 YO NEXT A ENT
11. an be the single most effective way to correct noise problems If a ground is not available install a ground rod as close to the system as possible Ensure all ground wires are single point grounds and are not daisy chained from one device to another Ground metal enclosures around the system A loose wire can act as a large antenna introducing noise into the system so tighten all connections in your system Loose ground wires are more susceptible to noise than the other wires in your system Review Chapter 2 Installation Wiring and Specifications if you have questions regarding how to ground your system Electrical noise can enter the system through the power source for the PLC and I O circuits Installing an isolation transformer for all AC sources can correct this problem DC sources should be well grounded good quality supplies Separate input wiring from output wiring Never run low voltage I O wiring close to high voltage wiring 9 10 DL06 Micro PLC User Manual 3rd Edition Rev C Chapter 9 Maintenance and Troubleshooting EEEEEBGUGGGGGLIGIULLU OOSCSLLLLRLRLALCGLECPOECODGLQOSO SO ORQO GEC EQOPLLLULAILLLLLULULLELLLALLLLLLULULL ZLSLIGLLLLILLAULLULELLLULULLLLEUGULZ EDOLLIGCKOULKUL Machine Startup and Program Troubleshooting The DL06 Micro PLCs provide several features that can help you debug your program before and during machine startup This section discusses the following topics which can be very helpful Progra
12. blems with the system In normal runtime operation only the RUN and PWR indicators are on The table below is a quick reference to potential problems Indicator Status Potential Problems System voltage incorrect PLC power supply faulty CPU programming error CPU in program mode RUN Green LED flashing CPU in firmware upgrade mode Electrical noise interference Internal CPU defective CPU Blinking Red LED Low backup battery refer to page 3 8 PWR Green LED off RUN Green LED off CPU Red LED on PWR Indicator In general there are three reasons for the CPU power status LED PWR to be OFF 1 Power to the unit is incorrect or is not applied 2 PLC power supply is faulty EJ 3 Other component s have the power supply shut down If the voltage to the power supply is not correct the PLC may not operate properly or may not operate at all Use the following guidelines to correct the problem WARNING To minimize the risk of electrical shock always disconnect the system power before inspecting the physical wiring 1 First disconnect the external power 2 Verify that all external circuit breakers or fuses are still intact 3 Check all incoming wiring for loose connections If you re using a separate termination block check those connections for accuracy and integrity 4 If the connections are acceptable reconnect the system power and verify the voltage at the DL0G power input is within
13. bles any changes to the discrete point by the CPU For example if you enable bit override for X1 and X1 is off at the time the CPU will not change the state of X1 This means that even if X1 comes on the CPU will not acknowledge the change Therefore if you used X1 in the program it would always be evaluated as off in this case If X1 was on when the bit override was enabled then X1 would always be evaluated as on There is an advantage available when you use the Bit Override feature The Regular Forcing is not disabled because the Bit Override is enabled For example if you enabled the Bit Override for YO and it was off at the time the CPU would not change the state of YO However you can still use a programming device to change the status If you use the programming device to force YO on it will remain on and the CPU will not change the state of YO If you then force YO off the CPU will maintain YO as off The CPU will never update the point with the results from the application program or from the I O update until the Bit Override is removed from the point 9 16 DLO06 Micro PLC User Manual 3rd Edition Rev C Chapter 9 Maintenance and Troubleshooting IR t J X The following diagrams show how the bit override works for both input and output points The example uses a simple rung but the concepts are similar for any type of bit memory Program R
14. er status display Below are the keystrokes to call the status display for Y10 Y20 From a clear display use the following keystrokes to display the status of Y10 Y20 STAT NEXT ub 5 ENT Y 20 Y 10 UbpbBubpubpHum gg dgdg0NCUN Override bit is on Point is on DLO06 Micro PLC User Manual 3rd Edition Rev C G 19
15. ete points to accumulator STR STRN Store greater than or equal Store less than Comparative Boolean Output accumulator to discrete points Shift accumulator right AND ANDN And greater than or equal And less than Comparative Boolean Shift accumulator left 9 14 DL06 Micro PLC User Manual 3rd Edition Rev C Numeric constant Chapter 9 Maintenance and Troubleshooting Run Time Edit Example We ll use the program logic shown to describe t our how this process works In the example we ll change X0 to C10 Note the example assumes you have already placed the CPU in Run Mode Use the MODE key to select Run Time Edits MODE CO NEXT NEXT ENT MODE CHANGE RUN TIME EDIT Press ENT to confirm the Run Time Edits Note the RUN LED on the D2 HPP MODE CHANGE Handheld starts flashing to indicate RUNTIME EDITS Run Time Edits are enabled Find the instruction you want to change X0 SHFT SHFT FD REF n A 00000 STR XO EH Press the arrow key to move to the X Then enter the new contact C10 gt Sl selic 1 5 115 1 og RUNTIME EDIT STR C10 Press ENT to confirm the change Note once you press ENT the next address is displayed OR CO DLO06 Micro PLC User Manual 3rd Edition Rev C e
16. iagnostics Diagnostics Your DLO6 Micro PLC performs many pre defined diagnostic routines with every CPU scan The diagnostics can detect various errors or failures in the PLC The two primary error classes are fatal and Zz non fatal Fatal Errors Fatal errors are errors which may cause the system to function improperly perhaps introducing a safety problem The CPU will automatically switch to Program Mode if it is in Run Mode Remember in Program Mode all outputs are turned off If the fatal error is detected while the CPU is in Program Mode the CPU will not allow you to transition to Run Mode until the error has been corrected Some examples of fatal errors are Power supply failure Parity error or CPU malfunction Particular programming errors g 8 Non fatal Errors Non fatal errors are errors that need your attention but should not cause improper operation They do not cause or prevent any mode transitions of the CPU The application program can use special relay contacts to detect non fatal errors and even take the system to an orderly shutdown or switch the CPU to Program Mode if desired An example of a non fatal error is Particular programming errors The programming devices will notify you of an error if one occurs while online DirectSOFT provides the error number and an error message The handheld programmer displays error numbers and short descriptions of the error Appendix B has a complete list of error
17. ing BE Special Instructions There are several instructions that can be used to help you debug your program during machine startup operations END PAUSE STOP END Instruction If you need a way to quickly disable part of the program just insert an END statement prior to the portion that should be disabled When the CPU encounters the END statement it assumes that is the end of the program The following diagram shows an example Normal Program New END disables X10 and Y1 XO x2 YO xo x2 YO CJ C2 X1 x3 X4 X1 x3 X4 1 1 1 1 X10 Y1 gt eno 2 X10 gh END HI V PAUSE Instruction This instruction provides a quick way to allow the inputs or other logic to operate while disabling selected outputs The output image register is still updated but the output circuits are not For example you could make this conditional by adding an input contact or CR to control the instruction with a switch or a programming device Or you could just add the instruction without any conditions so the selected outputs would be disabled at all times Normal Program PAUSE disables YO and Y1 XO X2 YO Yo Y1 C Pause X1 X3 X4 Ia XO X2 YO i 2 X10 YI X1 X3 X4 C2 1 4 Z X10 Y1 ivo A 2 GD STOP Instruction Sometimes during machine startup you need a way to quickly turn off all the outpu
18. lue SP15 Test stop mode SP63 Acc result is zero SP16 Terminal Program mode SP64 Half borrow occurred SP17 Forced stop SP65 Borrow occurred SP20 STOP instruction was executed SP66 Half carry occurred SP22 Interrupt enabled SP67 Carry occurred System Monitoring Relays SP70 Result is negative sign SP36 Override setup SP71 Pointer reference error SP37 SP73 Overflow Scan control error SP40 Critical error SP75 Data is not in BCD SP41 SP76 Load zero Non critical error SP42 Diagnostics error SP44 Program memory error SP45 1 0 error SP46 Communications error SP50 Fault instruction was executed SP51 Watchdog timeout SP52 Syntax error SP53 Cannot solve the logic SP54 Communication error SP56 Table instruction overrun DLO06 Micro PLC User Manual 3rd Edition Rev C 9 3 Chapter 9 Maintenance and Troubleshooting MM MM D PGBu Ou DL06 Micro PLC Error Codes These errors can be generated by the CPU or by the Handheld Programmer depending on the actual error Appendix B provides a more complete description of the error codes The errors can be detected at various times However most of them are detected at power up on entry to Run Mode or when a Handheld
19. m Syntax Check Duplicate Reference Check Special Instructions Run Time Edits Forcing I O Points Syntax Check Even though the Handheld Programmer and Direct SOFT provide error checking during program entry you may want to check a program that has been modified Both programming devices offer a way to check the program syntax For example you can use AUX 21 CHECK PROGRAM to check the program syntax from a Handheld Programmer or you can use the PLC Diagnostics menu option within Direct SOFT This check will find a wide variety of programming errors The following example shows how to use the syntax check with a Handheld Programmer Use AUX 21 to perform syntax check alrt 1 mm Em AUX 21 CHECK PRO 9 3 2 1 1 SYN 2 DUP REF Select syntax check default selection wr You may not get the busy display BUSY if the program is not very long One of two displays will appear Error Display example 00050 E401 MISSING END shows location in question REPI NO SYNTAX ERROR See the Error Codes Section for a complete listing of programming error codes If you get an error just press CLR and the Handheld will display the instruction where the error occurred Correct the problem and continue running the Syntax check until the NO SYNTAX ERROR message appears DLO06 Micro PLC User Manual 3rd Edition Rev C eg 11 Chapter 9 Maintenance and Troubleshoot
20. messages in order by error number Many error messages point to supplemental V memory locations which contain related information Special relays SP contacts also provide error indications refer to Appendix D 9 2 DLO06 Micro PLC User Manual 3rd Edition Rev C Es V memory Error Code Locations Chapter 9 Maintenance and Troubleshooting The following table names the specific memory locations that correspond to certain types of error messages Error Class Error Category Diagnostic V memory User Defined Error code used with FAULT instruction V7751 System Error Fatal Error code V7755 Major Error code V7756 Minor Error code V7757 Grammatical Address where syntax error occurs V7763 Error Code found during syntax check V7764 CPU Scan Number of scans since last Program to Run Mode transition V7765 Current scan time ms V7775 Minimum scan time ms V7776 Maximum scan time ms Special Relays SP Corresponding to Error Codes The special relay table also includes status indicators which can indicate errors For a more detailed descripti CPU Status Relays on of each of these special relays refer to Appendix D V7777 Accumulator Status Relays SP11 Forced Run mode SP60 Acc is less than value SP12 Terminal Run mode SP61 Acc is equal to value SP13 Test Run mode SP62 Acc is greater than va
21. oint is on Solid fill indicates point is on seri us Ps oo 97 Lins BIT FORCE Y10 From a clear display use the following keystrokes to force Y10 OFF No fill indicates point is off No fill indicates point is off SHFT MS ur SHFT rid BIT FORCE Y10 L 9 18 l DLO06 Micro PLC User Manual 3rd Edition Rev C Chapter 9 Maintenance and Troubleshooting Bit Override Forcing From a clear display use the following keystrokes to turn on the override bit for Y10 Solid fill indicates point is on SET ON o ST ms BIT FORCE SET Y 10 Small box indicates override bit is on Note at this point you can use the PREV and NEXT keys to move to adjacent memory locations and use the SHFT ON keys to set the override bit on From a clear display use the following keystrokes to turn off the override bit for Y10 Solid fill indicates point is on for Y10 Solid fill indicates point is on S RST gt ON o NS BIT FORCE RST Y 10 Small box is not present when override bit is off Like the example above you can use the PREV and NEXT keys to move to adjacent memory locations and use the SHFT OFF keys to set the override bit off EH Bit Override Indicators Override bit indicators are also shown on the handheld programm
22. ppendix B The RUN indicator will flash blink whenever the CPU is in the firmware upgrade mode CPU Indicator If the CPU indicator is on a fatal error has occurred in the CPU Generally this is not a programming problem but an actual hardware failure You can power cycle the system to clear the error If the error clears you should monitor the system and determine what caused the problem You will find this problem is sometimes caused by high frequency electrical noise introduced into the CPU from an outside source Check your system grounding and install electrical noise filters if the grounding is suspected If power cycling the system does not reset the error or if the problem returns you should replace the CPU If the CPU indicator is blinking the backup battery is low refer to page 3 8 Communications Problems If you cannot establish communications with the CPU check these items The cable is disconnected The cable has a broken wire or has been wired incorrectly The cable is improperly terminated or grounded The device connected is not operating at the correct baud rate 9600 baud The device connected to the port is sending data incorrectly or another application is running on the device A grounding difference exists between the two devices Electrical noise is causing intermittent errors The PLC has a bad communication port and should be replaced For problems in communicating with DirectSOFT on
23. ror Display example shows location in question If you get an error just press CLR and the Handheld will display the instruction where the error occurred Correct the problem and continue running the Duplicate Reference check very long You may not get the busy display if the program is not m AUX 21 CHECK PRO 1 SYN 2 DUP REF BUSY 00024 E471 DUP COIL REF Syntax OK display Na DEERE until no duplicate references are found NOTE You can use the same coil in more than one location especially in programs containing Stage instructions and or OROUT instructions The Duplicate Reference check will find occurrences even though they are acceptable DLO06 Micro PLC User Manual 3rd Edition Rev C G 13 Chapter 9 Maintenance and Troubleshooting Run Time Edits The DL06 Micro PLC allows you to make changes to the application program during Run Mode These edits are not bumpless Instead CPU scan is momentarily interrupted and the outputs are maintained in their current state until the program change is complete This means if the output is off it will remain off until the program change is complete If the output is on it will remain on WARNING Only authorized personnel fully familiar with all aspects of the application should make changes to the program Changes during Run Mode become effective immediately Make sure you thoroughly consider the impact of any changes to minimize the risk
24. specification If the voltage is not correct shut down the system and correct the problem 5 If all wiring is connected correctly and the incoming power is within the specifications the PLC internal supply may be faulty The best way to check for a faulty PLC is to substitute a known good one to see if this corrects the problem The removable connectors on the DL06 make this relatively easy If there has been a major power surge it is possible the PLC internal power supply has been damaged If you suspect this is the cause of the power supply damage consider installing an AC line conditioner to attenuate damaging voltage spikes in the future 9 6 l DLO06 Micro PLC User Manual 3rd Edition Rev C Chapter 9 Maintenance and Troubleshooting IBERIA t i RUN Indicator If the CPU will not enter the Run mode the RUN indicator is off the problem is usually in the application program unless the CPU has a fatal error If a fatal error has occurred the CPU LED should be on You can use a programming device to determine the cause of the error Both of the programming devices Handheld Programmer and DirectSOFT will return an error message describing the problem Depending on the error there may also be an AUX function you can use to help diagnose the problem The most common programming error is Missing END Statement All application programs require an END statement for proper termination A complete list of error codes can be found in A
25. ts and return to Program Mode You can use the STOP instruction When this instruction is executed the CPU automatically exits Run Mode and enters Program Mode Remember all outputs are turned off during Program Mode The following diagram shows an example of a condition that returns the CPU to Program Mode 9 1 2 l DL06 Micro PLC User Manual 3rd Edition Rev C Normal Program Chapter 9 Maintenance and Troubleshooting IRE A amp XO X2 YO C2 X1 x3 X4 A X5 Y1 GD STOP puts CPU in Program Mode X7 ED X0 X2 YO C X1 x3 X4 1 1 X5 Y1 hs CD In the example shown above you could trigger X7 which would execute the STOP instruction The CPU would enter Program Mode and all outputs would be turned off Duplicate Reference Check You can also check for multiple uses of the same output coil Both programming devices offer a way to check for this condition For example you can AUX 21 CHECK PROGRAM to check for duplicate references from a Handheld Programmer or you can use the PLC Diagnostics menu option within DirectSOFT The following example shows how to perform the duplicate reference check with a Handheld Programmer Use AUX 21 to perform syntax check C CLR 2 B AUX ENT Select duplicate reference check gt ENT One of two displays will appear Er
26. ung Override holds XO YO previous state and disables 67 image register update by CPU XO override enabled XO at input module XO in image register YO in image register The following diagram shows how the bit override works for an output point Notice the bit override maintains the output in the current state If the output is on when the bit override is enabled then the output stays on If it is off then the output stays off Program Rung Override holds X0 YO previous state and disables co image register update by CPU YO override enabled X0 at input module YO in image register YO at output module The following diagram shows how you can use a programming device in combination with the bit override to change the status of the point Remember bit override only disables CPU changes You can still use a programming device to force the status of the point Plus since bit override maintains the current status this enables true forcing The example shown is for an output point but you can also use the other bit data types Program Rung The force operation from the XO YO programming device can still o change the point status YO override enabled XO at input module
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