This application note provides clarification of a PowerFlex40 (PF40) used in multi-drive mode, and the advantages and dis-advantages of its usage.

Transcription

1 Introduction This application note provides clarification of a PowerFle40 (PF40) used in multi-drive mode, and the advantages and dis-advantages of its usage. The PowerFle40 drive has been designed to be connected via a network, and controlled by a PLC. PowerFle 40 up to 5 drives on 1 Up to 4 PowerFle 4 s w/ 3rd Party Terminating Resistor The drive is designed to allow a network adapter card to be fitted, so that the drive can be part of a specific network. 22-COMM-C ControlNet 22-COMM-D DeviceNet 22-COMM-E EtherNet/IP 22-COMM-P Profibus DP The drive can operate in two different modes, selected by a jumper/switch on the adapter single drive mode 1 network adapter per drive multi drive mode 1 network adapter for up to 5 drives. In multi-drive mode, the PF40 acts as the host connection to the network, and communicates to the other drives over the RS-485 connection (Drive Serial Interface) running at baud. Each drive (which can be PF4 s or PF40 s) can be independently controlled, with status and feedback, and single parameters to each drive can be read / written by a telegram. Additional to the network cards, a Compact I/O card for DSI 1769-SM2 is available. This I/O card has 3 channels and can be used with a Micrologi 1500 or CompactLogi platform, to control 3 drives in single drive mode or 15 drives in multi-drive mode. As using this configuration doesn t need a host drive, then all drives behave in the following document as a slave drive. This architecture below details how multi-drive control is configured for DeviceNet, with the ability to control each slave in both local and remote. The other networks and the 1769-SM2 work in a similar manner, with similar benefits, unless specifically mentioned. PowerFle40 multi-drive control.doc Page 1 of 6

2 Architecture and Configuration. The PF40 drive host drive in the above diagram, is intended to be controlled only by the PLC, and is configured as a multidrive with 3 drives. Drive 0 (the PF40) is at the DSI default address of 100 Drive 1 = DSI address 101 Drive 2 = DSI address 102 The 22-COMM-D parameters of the PF40 are configured to specify that there are 3 drives and their addresses. As can be seen from the I/O map, each drive has Logic command and Reference words going from the PLC, and Logic Status and Feedback words going from the drives and input to the PLC. This means 2 words input (4bytes) and 2 words output (4bytes) per drive. Therefore 3 drives is 12 bytes input and 12bytes output, so we need to map the DeviceNet scanner for 12 bytes in and 12 bytes out. Setting para 15 in the 22-COMM-D [DSI I/O Config] = Drives 0-2 also specifies 12 bytes. PowerFle40 multi-drive control.doc Page 2 of 6

3 TIP To adjust the parameters of the PF40 drive and the Devicenet adapter, ensure the 22-COMM-D adapter jumper is in single drive mode, so that you can plug in the 22-SCM-232 into the RJ45 plug on the drive with DriveEplorer. When parameters have been changed, power down the drive and change jumper back to multi-drive. Normal operation The drives are controlled from the PLC via the Logic Command word (para P036 = 5). Each of the 3 drives has its own Logic Command word for complete independent control. Additionally the speed reference of the drive is sent from the PLC as a value of 0 to 500 = 0 to 50.0Hz for eample. The PF40 host drive is set to control via the PLC (para P038 = 5). As the slave drives are selectable local / remote, Digital Input 1 on the slave drives is configured for Comm Control (para A051 = 6). Also the slave drives are configured to control from an eternal potentiometer (para P038 = 2) when in local. This means that when input 1 = high, then the drive is controlled by the network, and when input 1 = low then the drive is controlled from the terminal block start/stop and the eternal potentiometer. So when digital input 1 = low, the drive is on local control. Local LED The LED above the keypad pot is on, when the drive is on Local control. Additionally the status of each drive is sent to the PLC via the Logic Status word. Each of the 3 drives has its own Logic Status and Feedback words for complete independent control. Access to Multi-Drive Parameters when operational. When everything is configured correctly, and the PLC and drives are running, it is possible to use DriveEplorer or Drive Eecutive / DriveObserver to access the drive parameters. However as the RJ45 plug on each drive is used for DSI control, it is not possible to plug in a peripheral to access parameters. i.e. splitters not allowed, and DSI control ecludes peripheral access. Therefore the software tool used will depend on the network / card selected, and whether there is a PowerFle 7 class drive on the network. PowerFle 7 class drives have the ability to route through the drive onto the network. PowerFle40 multi-drive control.doc Page 3 of 6

4 Using DriveEplorer DriveEplorer is designed to be used as a point to point serial connection with the 1203-SSS ( 7 class drives) or 22-SCM-232 ( 4 class drives) serial interfaces. However as the DSI is already used for control, we cannot use a 22-SCM-232. Therefore we need to connect onto a PowerFle 7 class drive using a SSS, and pass-through to the PF40 by using the serial to network connection. This can be used for networks of DeviceNet and ControlNet, but not Profibus DP or 1669-SM2. its IP address. DriveEplorer also has dedicated drivers for EtherNet/IP, so it is not necessary to connect via a PowerFle 7 class drive, but go direct to the drive via The screenshot above details a PF40 in multi-drive with 1 slave drive on ControlNet accessed via a PF70 on Node 3. Note that Node 5 (PF40) shows the parameters for the PF40 host, PF4 slave, and the 22-COMM-C ControlNet adapter parameters. Note that DriveEplorer can only be used with the 1769-SM2 in single drive mode. Using DriveEecuitive / DriveObserver DriveEecutive uses RSLin software to define a path to the drives. Then you navigate to the network and drive you need to access. The RSLin eample details connection via EtherNet/IP to a CompactLogi at IP , then passing via the backplane to the 1769 bus, and onto the DeviceNet card at slot 1. Now we can select the PF40 host on DeviceNet at Node 23. As with DriveEplorer the screenshot shows the PF40 multi-drive host, and the 2 PF4 slaves, and the 22-COMM-D DeviceNet parameters. As we used RSLin to connect to the drives, this will work on ControlNet, DeviceNet, EtherNet/IP. Additionally it will work on the 1769-SM2 in single drive mode or with DE >v4.01 in multidrive It will not work on Profibus DP, as RSLin doesn t support pass-through. PowerFle40 multi-drive control.doc Page 4 of 6

5 When the host drive powers down and up.. Once a connection is validated and made onto a network, this will be maintained until the connection is broken by a power down or communication errors. When the drives are powered for the first time, the host drive with the 22-COMM-D will compare the configuration size (para 15 of the 22-COMM-D), to the actual number of drives connected. They sizes must match in order for the connection to be validated. If a drive is missing, then the 22-COMM-D will see a mismatch and will refuse a connection to the DeviceNet scanner. So communication to the drives will not be permitted, and the DeviceNet scanner will flash error 83 and then the node address. When all the relevant slave drives are reconnected, the 22-COMM-D will stop issuing an error. As the scanner checks the 22-COMM-D periodically every 10s, the DeviceNet scanner will then validate the connection, and control of the drives will be permitted. Although a similar situation occurs with a ControlNet or EtherNet connection, there is a significant difference, as the host drive and adapter doesn t wait for the slaves to return. The loss of the host drive is indicated with a warning symbol showing up on the drive in the I/O tree of RSLogi. However when the host drive returns, the connection is validated, and so the host drive will communicate. When a slave drive powers down / unplugged and up.. In some circumstances it may be necessary to power down a slave drive or remove the DSI plug. e.g. isolate the drive to clear a blockage, or replace a faulty drive. If the DSI plug is removed, then the drive will generate F81 fault = Comms Loss (default condition) If a slave drive is powered down using the eample above, the 22-COMM-D will compare the configuration size (para 15 of the 22-COMM-D), to the actual amount of drives connected e.g. was 12 bytes in & 12 bytes out, but with 1 drive removed, it is actually 8 bytes in & 8 bytes out. Hence the 22-COMM-D knows that a drive is down, and sends zeros to the input word in the scanner for the drive that is missing, and the PORT and MOD LEDs of the 22-COMM-D flash red. As the scanner connection is still made, no errors are sent to the scanner, and all the other drives operate and control as normal. Other adapters behave similarly, but with just the PORT LED flashing red. Once the drive is powered back up, clearing the fault on the returning drive, puts the 22-COMM-D LEDs back to green, and the input word now reflects the actual drive status. So a clear fault is required! When operating digital input 1 = low (local control), the configuration of the 22-COMM-D is not changed (12 bytes = 3 drives), so the host adapter shows 3 green LED s. As the scanner / PLC has no idea that a drive is missing, so it is important that the user adds some additional program in the PLC, to see if the drive is still attached and controllable. One way to do this is to check the drive status bits, to see if they are all zero. Drive status bits at zero should only be present transiently, or when the drive has powered down or stopped communicating. An eample of a circuit to check the drive status word is shown below: PowerFle40 multi-drive control.doc Page 5 of 6

6 When the drive is connected to the network, the status word of the drive should always have a value (even when stopped) e.g decimal. The program above checks whether the status word is zero (the drive has powered down), and to provide some hysteresis starts a timer. When timed out, it creates the signal ENET_PF40_control_lost. Once this situation has been detected, then it is good practice to reset the start command in the PLC program. Otherwise the drive will start as soon as power to the drive is restored and it is connected. Note that several seconds can elapse before the status is zero, due to the energy stored in the dc bus of the drive. Advantages & Disadvantages of Multi-Drive Control The use of Multi-drive control does provide a more cost effective solution to controlling drives on a network. However it does have some drawbacks which need to be considered before selecting this solution: As Multi-Drive DSI works at 19200baud, it takes a longer time to control the drive and get a response. i.e. 25ms per drive passing through the host 5 drives = 125ms All drives of a multi-drive loop must power up for the first connection to be made. Loss of the host drive means a loss of comms to all drives of the multi-drive loop. Access to drive parameters is only possible with DriveEecutive (unless have 7 class drive on network) Automatic Drive Replacement on DeviceNet only works with single drive mode. Etra code in the PLC to detect loss of comms to the slaves. No peripherals can be connected when multi-drive DSI control is used. This application note should be used in conjunction with the drive and adapter user manuals, and the DSI wiring should be installed as the application note DSI cabling.pdf. PowerFle40 multi-drive control.doc Page 6 of 6