ELECTRICAL & COMPUTER ENGINEERING TECHNOLOGY. The Compact Logix PLC will be utilized to control the operation of the PowerFlex-40 VFD.

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1 SOUTHERN POLYTECHNIC STATE UNIVERSITY ECET 4530 RSLogix Tutorial Modules ELECTRICAL & COMPUTER ENGINEERING TECHNOLOGY Module B Control of the PowerFlex 40 VFD Introduction: The Compact Logix PLC will be utilized to control the operation of the PowerFlex-40 VFD. Procedure: Note in order to perform this module, both the physical control system components and the RSLogix 5000 software should already be setup as instructed within the Initial Control System Setup document provided with the individual RSLogix Tutorial Modules. If the initial setup procedure has not yet been completed, please refer to that document before attempting to perform this module. Initial Configuration of the PowerFlex 40 (PF40) VFD 1. Reset the VFD to its default configuration by accessing the Basic Program Group P041 and setting its value to one (1) using the following procedure: a) Press the Esc button on the front panel of the PF40 two times. The left-most character ( d for Display Group) in the LED display should be flashing. b) Press the button once such that the left-most character changes to a P for Basic Program Group. This allows you to view and/or change the settings within this group. c) Press the Sel button once such that the right-most character of the display is flashing, and then use the or the button to change to program P041. Once P041 is displayed, press the button to choose this program. d) Use the or the button to change the displayed value from a 0 to a 1 and press. This will reset the PF40 to default conditions. e) The PF40 s display should now be flashing F048. Fault 48 means that the VFD s parameters were reset to their default values. f) Press the Esc button to acknowledge and clear the fault. 2. In a similar manner, change the following parameter(s) of the VFD as stated below: P036 From 0 to 5 This allows the PF40 to receive the Start command from the Comm Port instead of the keypad. P038 From 0 to 5 This allows the PF40 to receive its Fpeed Reference value from the Comm Port instead of the potentiometer on the front panel. P039 From 10 to 4 This changes the acceleration rate [Accel Time 1] from 10 to 4 seconds. P040 From 10 to 4 This changes the deceleration rate [Decel Time 1] from 10 to 4 seconds. Note there is an alternate accel/decel rate pair [Accel Time 2 / Decel Time 2] whose values are stored in Advanced Program Groups A067 and A068 respectively. For this experiment, the alternative rates will be left at their default values of 10 seconds. 3. Access the Display Group d012 and verify that it displays 55. This group displays the current settings of P036 and P038 as a 2-digit number

2 Control System Description/Components A two-pushbutton, stop/start controller will be developed using the VFD instead of a contactor to provide power to the Induction motor. Additionally, the controller will allow for both forward and reverse operation of the motor. To accomplish this task, the PLC will be configured such that it utilizes: Pushbutton-A wired to Input-0 of the PLC as the Stop button, Pushbutton-B wired to Input-1 of the PLC as the Start button, The two-position switch wired to Inputs-3 and 4 of the PLC to specify the direction of rotation. Furthermore, the PLC will communicate with the VFD using the Ethernet network that was previously configured during the Initial Control System Setup module. RSLogix 5000 Software Creating the Ladder Diagram (Program) 4. The Routine Editor window should be displaying a blank ladder diagram as shown to the right: 5. Choose the Bit tab in the New Component toolbar. 6. Place an OTE instruction on the top rung of the ladder diagram. Note the OTE will appear on the right end of the rung after being placed. 7. Right-click on the? above the instruction and choose New Tag in the menu that appears. 8. Name the tag Clear_Faults. 9. Click on the down-arrow in the Type: field and change the type from Base to Alias. 10. The Alias For: field should now be active. Click the down-arrow in the Alias For: field to open a menu that displays a list of the previously defined tags

3 11. Locate the VFD in the menu and expand the its output tags by clicking on the next to VFD:O. 12. Double-click on VFD:O.ClearFaults to select that output tag. 13. ClearFaults should now appear in the Alias For: field in the New Tag window. Click OK to close the window. 14. The aliased Clear_Faults OTE should appear on the top rung of the ladder daiagram as shown below: ClearFaults: VFD:O.ClearFaults is a tag that was automatically defined when the PowerFlex 40 was added as a new module when initially configuring the RSLogix software. A fault may occur on the PF40 drive for a variety of reasons, such as whenever the drive is reset to default configuration or the whenever the drive loses communication with the PLC (which happens whenever the PLC is switched from Run to Program mode). When a fault occurs, it must first be cleared before the drive is able to operate normally. A fault on the PF40 may be cleared either by pressing the ESC button on the keypad of the drive or by setting the ClearFaults bit. Placing the Clear_Faults OTE on the top rung of the ladder diagram with no additional instructions causes the OTE to remain active at all times. Thus, the ClearFaults bit will be set every time the top rung of the program is scanned, immediately resetting any faults that occur on the PF40 without requiring the attention of an operator. 15. Add a new rung into your routine by dragging a Rung icon in the Bit tab of the New Component toolbar into your ladder diagram just below rung-0. Note a green circle will appear at the location that the rung will be placed based on the position of the mouse pointer. Release the mouse when the green circle appears between rung-0 and the End-rung as shown to the right: 16. Place an XIC instruction on the new rung and define its tag as: Name Start_Motor Type Alias Description Run at 60Hz Alias For: Local:1:I.Data.1-3 -

4 17. Place an ONS (One Shot) from the Bit tab of the New Component toolbar to the right of the Start_Motor instruction. 18. Define a new tag for the ONS with the Name Oneshot_1. ONS Operation: ONS stands for One Shot. When the XIC on the rung closes, the ONS will be triggered. The ONS then enables the instruction connected to its output (placed immediately to the right of the ONS). Yet, unlike an XIC that continuously enables any instruction connected to its output as long as the XIC is closed, the ONS s output is only enabled for a single rung scan, after which the ONS s output will be disabled for successive rung scans even if the XIC remains closed. In order to re-trigger the ONS, its input must first be disabled and then be re-enabled. Thus, the XIC must first open and then reclose before the ONS will trigger again. 19. Add a Branch to the right of the Start_Motor button and place an OTL (Output Latch) instruction on the upper path and an OTU (Output UnLatch) instruction on the lower path. OTL Operation: OTL stands for Output Latch. When the rung to the left of the OTL becomes energized, the OTL will set the bit of the tag assigned to that OTL instruction. Yet, unlike an OTE that will reset the bit when the rung is de-energized, the OTL latches the bit, holding it high even if the rung is de-energized. Once a bit is latched, the only way to reset the bit is to use an OTU (Output UnLatch) instruction. OTU Operation: OTU stands for Output UnLatch. When the rung to the left of the OTU becomes energized, the OTU will unlatch (reset) the bit of the tag assigned to that OTU instruction. When the rung is de-energized, no further change occurs to the bit. 20. Define the tags of the OTL and OTU as follows: Upper Branch OTL Name VFD_Start Type Alias Alias For: VFD:O.Start Lower Branch OTU Name VFD_Stop Type Alias Alias For: VFD:O.Stop Note VFD:O.Start and VFD:O.Stop appear above VFD:O.ClearFaults in the VFD output tag menu Start: VFD:O.Start is a tag that was automatically defined when the PowerFlex 40 was added as a new module during the initial configuration of the RSLogix software. The VFD must first be activated before it will supply an output voltage to the Induction Motor. By default, the PF40 is activated when the Start button on the keypad of the drive is pressed. But, the Basic Program Group P036 parameter was changed from 0 to 5 at the beginning of this module, reconfiguring the drive to receive the Start command from the Comm (Ethernet) port instead of the keypad

5 Stop: VFD:O.Stop is a tag that was automatically defined when the PowerFlex 40 was added as a new module during the initial configuration of the RSLogix software. The VFD can be de-activated by pressing the Stop button on the keypad of the drive. When the Stop button is pressed, the output frequency of the drive will first be lowered to zero at the specified Decel rate programmed into the drive, after which the drive will become inactive. Once stopped, the drive must receive a Start command before it will again supply an output voltage to the Induction Motor. Setting the VFD:O.Stop bit has the same effect as pressing the Stop button on the keypad. Note that the drive will respond to both the Stop button and the VFD:O.Stop bit. Rung-1 of your ladder diagram should appear as follows: Pressing the Start_Motor button will cause the One Shot to activate the Latch/UnLatch pair, setting the Start bit and resetting the Stop bit of the VFD one time, even if the button is held-in. The purpose of the One Shot may not be readily apparent if only normal system operation is considered. A well-designed control system is able to account for component failures, such as a sticky start button. If the normally-open Start_Motor button fails and sticks in the closed position, the system will continuously keep latching the Start bit even if a Stop_Motor button is pressed and released. Placing a One Shot after the Start_Motor button allows for the motor to be stopped if the Start button sticks, because the One Shot requires the Start_Motor instruction to open and reclose before it will reactivate the OTL instruction. 21. Add a new rung to your ladder diagram just below rung-1 using the Rung icon. 22. Place an XIC instruction on the new rung. 23. Copy the tag from the rung-1 XIC onto the new XIC by left-clicking and holding the mouse pointer over the Start_Motor tag and dragging it down to the undefined XIC. A green oval will appear next to the? indicating that the tag will be copied to that instruction if the mouse is released in the present location. 24. Place an ONS to the right of the XIC and name the new tag OneShot_ Choose the Move/Logical tab in the New Component toolbar

6 26. Place a MOV (Move) instruction to the right of OneShot_ Right-click on the? in the Source field and define a new tag for the MOV instruction named Freq_60. MOV Operation: The MOV (Move) command is used to copy data from the memory location referenced by the Source tag to the memory location referenced by the Dest tag provided they are of the same Type. The Dest (Destination) tag may be local to the PLC or it may be on a remote device such as the VFD. The current value of the Source data will appear in the field with the?? below the source s tag name. The current value of the Dest data will appear in the field with the?? below the destination s tag name. By double-clicking on either of the?? fields, the default value for the data at that location can be changed. 28. Double-click on the?? field below the Source tag and change the value to Double-click on the? in the Dest field. 30. Click on the down-arrow that appears to open the tag menu. 31. Locate and double-click VFD:O.FreqCommand in the output tag section for the VFD to choose that as the destination tag. The?? below the destination tag name should default to zero (0). FreqCommand: VFD:O.FreqCommand is a tag that was automatically defined when the PF40 was added as a new module during the initial configuration of the RSLogix software. The value stored in the FreqCommand location is the output voltage frequency at which the drive is commanded to operate. If the value is changed such that it is different than the current output frequency then the drive will change its output to the newly commanded frequency. The rate at which the drive changes its output frequency is defined by the value stored in the VFD s active AccelRate or DecelRate memory location depending on whether the change results in a frequency increase or decrease. Thus, copying the Source value to the FreqCommand location will cause the VFD to linearly vary its output from the original frequency to the commanded frequency at the specified rate. Note if the drive is inactive (Start bit not set) when the FreqCommand is sent, the commanded frequency will change but the output will remain inactive. If the Start bit is set after the FreqCommand value is changed, the VFD will immediately accelerate to the previously commanded frequency. Note the VFD considers the last digit of the value contained in FreqCommand as tenths of Hertz. Thus, the value 600 will be interpreted as 60.0Hz

7 Rung-2 of your ladder diagram should appear as follows: Along with latching the Start bit when the Start_Motor button is pressed (rung-1), Start_Motor will also trigger OneShot_2, causing it to activate the Move instruction for one scan of the rung. The MOV instruction copies the 60.0Hz frequency to the FreqCommand location of the VFD. Since the VFD was previously activated when its Start bit was latched on rung-1, the VFD will immediately begin to supply an output voltage to the Induction machine, the frequency of which will rise at the rate defined in its active AccelRate memory location. 32. Add the following two rungs to your ladder diagram and define the tags for the instructions contained on those rungs as shown in the figure below: Pressing the Stop_Motor button will have the opposite effect of the Start_Motor button. Stop_Motor will result in a frequency of zero (0) copied into the FreqCommand location, the Stop bit of the VFD to be latched, and the Start bit of the VFD to be unlatched. Note Unlatching the Start bit and latching the Stop bit without the Move 0Hz instruction will cause the VFD to decrease its output frequency to zero and deactivate its output, but the commanded frequency will remain at 60.0Hz, causing the drive to immediately accelerate back to 60.0Hz if reactivated

8 33. Once again, add the following two rungs to your ladder diagram and define the tags for the instructions contained on those rungs as shown in the figure below: Forward/ Reverse: VFD:O.Forward and VFD:O.Reverse are a tags that were automatically defined when the PF40 was added as a new module during the initial configuration of the new module during the initial configuration of the RSLogix software. Setting the Forward bit and resetting the Reverse bit causes the VFD to provide a positive-sequence 3Φ voltage to the Induction machine which results in a Forward direction of rotation. Setting the Reverse bit and resetting the Forward bit causes the VFD to provide a negative-sequence 3Φ voltage to the Induction machine which results in a Reverse direction of rotation. Care must be taken not to set or reset both bits, as this can put the drive into an unstable operational state. Note Changing the direction from forward to reverse while the drive is operational will cause the drive to first decrease the output frequency to zero, and the increase to increase the output frequency back to the commanded frequency but with the opposite phase-sequence (rotational direction). The two-position switch is wired to the PLC such that it energizes Input-3 when in position-a and it energizes Input-4 when in position-b. Thus: The Forward XIC activates when the switch is in position-a, in-turn latching the VFD:O.Forward bit and unlatching the VFD:O.Reverse bit in the VFD, and The Reverse XIC activates when the switch is in position-b, in-turn latching the VFD:O.Reverse bit and unlatching the VFD:O.Forward bit in the VFD

9 34. Locate and click the icon at the top of the RSLogix 5000 main window. The RSLogix software will now check your ladder diagram for errors. If any errors are found, they will be reported in the field below your ladder diagram in the main window. 35. If any errors are reported, make the appropriate corrections until no more errors are reported. RSLogix 5000 Software Going Online with the Controller 36. Choose a path from the list of known controllers that has the correct IP Address for the PLC similar to that shown in the below figure if the path is not already set and click Go Online, or click on the downarrow next to the word Offline in the upper-left corner of the RSLogix main window and choose Go Online from the menu that appears if the path has already been set. 37. When the Connected to Go Online window appears stating that The open project has changes that aren t in the controller, choose Download. 38. A Download window will appear that will allow you to copy your program into the PLC s memory. Read the warning and then click Download. 39. If a pop-up appears asking if the controller should be switched back to Remote Run mode, click Yes. 40. The RSLogix 5000 software should now be online with the PLC such that the operational state of the PLC can be seen by viewing the ladder diagram. Components in the diagram that are energized are highlighted in green. Initially the Voltage Supply Rails and the XIC associated with the current position of the switch should be energized. 41. Verify that the PLC is functioning correctly (see the steps below). If any errors are detected, go back Offline and trouble-shoot your ladder diagram. With the switch set to the A-position, press the Start button and verify that the VFD activates and accelerates the motor to an operational frequency of 60Hz. Press the Stop button and verify that the VFD decelerates the motor to an operational frequency of 0Hz and then deactivates. Flip the switch to the B-position and then press the Start button again. Verify that the VFD accelerates the motor in the reverse direction. While the motor is running, flip the switch back to the A-position observe the operation of the drive and motor. 42. Stop the motor when finished testing the system. You have completed Tutorial Module-B