SureServo2 Position Register Mode (PR Mode) Triggering from AutomationDirect
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(VID-SV-0086)
The SureServo 2 uses PR mode to program and execute paths in the drive for executing motion or logic. Today we discuss ways to trigger these paths. This video is a follow-up to the PR Mode video.
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In our previous video on Position Register or “PR” mode, we showed you the incredible capabilities available to you with path programming in the SureServo2 drive. It is important to understand that once you program a PR path, there are many ways to trigger it. Regardless of which trigger method is used, they all will execute the same path. In the PR mode configuration video, we only used the configuration software to trigger a PR path. While this is great for testing, and initial setup, it isn’t feasible to manually trigger a move over and over, when you need to run the move thousands of times per day, each day every year. The most common methods to command a PR path in a production environment are using the drive’s digital inputs or writing information using Ethernet or serial communications. The other options we discussed in the initial PR mode video were Capture, Compare, E-Cam and Event Triggering. These are all for more advanced and specialized motion applications and require a lot of other settings and understanding. They are all described in detail in the SureServo2 user manual, so we won’t be focusing on them today. Additionally, we cover triggering a PR path via communications in this video for Modbus/TCP, this video for Modbus/RTU, this video for implicit EtherNet/IP, and in this video for explicit EtherNet/IP so we also won’t be rehashing any of those. We will instead be focused on the final method for triggering a PR path in the SureServo2. This is done using the drive’s digital inputs. With the drive configuration we performed in the PR mode video, triggering PR Path #1 will start a four-path program that sends our linear slide to 0, then cycles between +3 inches and -3 inches. In our video today we are using a slightly different motion base, but the concept will be the same. Let’s also plan to add a 5th PR path trigger as an option to interrupt the cycle and return us to 0. To do this we will go to the PR Mode Setting screen and set Path 5 to be a point-to-point move that does not proceed to the next path. We will have this path interrupt any previous path. This will cause this path to be immediately executed overriding any currently running paths. We could also use an overlap move to have a blended transition when the active path enters its deceleration region. Since this path is going to run to a stop at 0, an overlap isn’t necessary so we will leave that off. The path will move to a position of 0, and we will use the same accel, decel, and velocity as the paths we programmed in the PR mode video. We can then write this path to the drive. To trigger PR Path #1, we will need to wire in a few digital inputs. Since we don’t know which digital inputs to wire just yet, this will require a little planning first. Remember that any servo motion requires the servo to be enabled, and to begin a PR path, we need to be able to select one of up to 100 different paths (0-99) as well as trigger them. Let’s take a look at the drive digital inputs in our SureServo2 Pro software. We can go to the top menu bar and select “Digital IO/Jog Control.” Here we see the default configuration for digital inputs and digital outputs. If we check the box for “Edit DI/O Item” it will allow us to change the settings for each digital input. DI1 is already set for Servo ON and it is set to Logic Condition A. “Servo ON” means the same thing as Servo Enable, and Logic Condition A means the input is normally open, so it will register as “ON” when current is flowing. If we look further down the table, we see that DI6 and 7 default to overtravel sensor inputs and DI8 is set to an override or machine stop input. All three are set to Logic B. Logic condition B is normally closed, so an input would register as “ON” when current is not flowing. This is very useful when you are using machine safety functions, such as a machine stop button or overtravel switches. These devices often use normally closed contacts so that a wire breaking will cause the system to respond the same as if the stop button was pressed, or an overtravel occurred. For SureServo2, digital inputs may be assigned as PR selection inputs. Each input represents a bit in the binary path number. PR Path 4 for example is the binary number 100, so it would be selected by having three digital inputs reserved for path selection, with the first two inputs off to represent the 0s, and the third input on to represent the 1. In our example, PR Path 5 is the highest we will need to select, so 3 inputs being reserved for path selection is sufficient. If we had more PR paths, we might need to reserve more digital inputs as our binary number got longer. Let’s set DI2-4 as our three-bit positions and we will use Logic A. As we assign each input, it is important that we select “OK” prior to moving to the next input otherwise the input will return to its previous setting as soon as I move on. With those three inputs assigned, the last thing we will need is an input to trigger the PR path we have selected. We will use DI5 for this. Alright. Now that we have our digital inputs assigned, we need to wire up the inputs to our control system. Let’s look at this wiring schematic from the manual. These inputs can be wired as sinking NPN inputs, or sourcing PNP inputs as we see here. With our inputs wired in, we are ready to start moving. I have the servo powered up, our linear slide is in the middle and the system is homed to Position 0. The SureServo2 Pro software actually tells us if any of the inputs or outputs are on, in real time. I just love how easy the software makes testing inputs and verifying that everything is wired up correctly. These status boxes are where we see if the input is ON or OFF. Using those boxes, we can see that I have DI1 on to enable the drive, as well as DIs 6, 7, and 8 all on to act as overtravel sensors and the machine stop button. Currently, our three PR selection inputs are all off, so if I were to turn on DI5 to trigger a PR move, the system would run PR Path 0, which is the homing routine. We don’t want to do this, so let’s trigger Path 1 instead. Remember that Path 1 will start a move to 0 inches, Path 2 will be a move to +3 inches and will start Path 3 after a pause. Path 3 will be a move to -3 inches and will start Path 4 after another pause. Path 4 will return back to Path 2 repeating the cycle indefinitely. If I turn on DI2 and leave DI 3 and 4 off, this corresponds to the binary number 001. I can now turn on DI5 to run PR Path 1. We see the linear slide move to positive 3 inches, pause for 1 second, then go backwards to negative 3 inches and repeat. Just like we saw in our PR mode video. So far, so good. Now let’s switch our PR mode selection bits to select Path 5. Remember that Path 5 is our interrupt, that will then return the linear slide back to 0. PR Path 5 is a binary number of 101, so I will have DI2 and DI4 on, and leave DI3 off. When I do this, nothing occurs because we have selected Path 5, but have not yet sent the trigger. If I now turn on DI5 to trigger the path, we see the cycle is interrupted and the linear slide moves back to 0. Perfect! We have now triggered multiple PR paths with digital inputs using the SureServo2. For further assistance please contact our award winning free technical support! We also have plenty more videos on SureServo2 setup and configuration for you to take a look at. To subscribe to our YouTube channel, click here.
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