Application Guide. Considerations for 32 Bit Integer Parameters in 16 Bit Processors. PowerFlex 700VC, PowerFlex 700S. Introduction.

Transcription

1 Topic: Drive Product: Introduction User Information Considerations for 32 Bit Integer Parameters in 16 Bit Processors PowerFlex 700VC, PowerFlex 700S An Application Guide provides generic information on features and functions of drive products and their implementation. Application Guides are not specific to any one application, but generically discuss application techniques and/or functions as part of an application. Solid state equipment has operational characteristics differing from those of electromechanical equipment. Safety Guidelines for the Application, Installation and Maintenance of Solid State Controls (Publication SGI-1.1 available from your local Rockwell Automation sales office or online at describes some important differences between solid state equipment and hard-wired electromechanical devices. Because of this difference, and because of the wide variety of uses for solid state equipment, all persons responsible for applying this equipment must satisfy themselves that each intended application of this equipment is acceptable. In no event will Rockwell Automation, Inc. be responsible or liable for indirect or consequential damages resulting from the use or application of this equipment. The examples and diagrams in this document are included solely for illustrative purposes. Because of the many variables and requirements associated with any particular installation, Rockwell Automation, Inc. cannot assume responsibility or liability for actual use based on the examples and diagrams. No patent liability is assumed by Rockwell Automation, Inc. with respect to use of information, circuits, equipment, or software described in this document. Reproduction of the contents of this document, in whole or in part, without written permission of Rockwell Automation, Inc. is prohibited. Related Publications The following publications should be referenced and followed when operating, configuring, or commissioning this drive product. These publications may be found on the literature library at ; Publication Title PowerFlex 700S Phase II Control User Manual PowerFlex 700S Phase I Control User Manual Pub Number 20D-UM006 20D-UM001 PFLEX-AP002A-EN-E.doc - June 28, 2005

2 Precautions Class 1 LED Product ATTENTION: Hazard of permanent eye damage exists when using optical transmission equipment. This product emits intense light and invisible radiation. Do not look into module ports or fiber optic cable connectors. General Precautions ATTENTION: This drive contains ESD (Electrostatic Discharge) sensitive parts and assemblies. Static control precautions are required when installing, testing, servicing or repairing this assembly. Component damage may result if ESD control procedures are not followed. If you are not familiar with static control procedures, reference Allen Bradley publication , Guarding Against Electrostatic Damage or any other applicable ESD protection handbook. ATTENTION: An incorrectly applied or installed drive can result in component damage or a reduction in product life. Wiring or application errors such as under sizing the motor, incorrect or inadequate AC supply, or excessive surrounding air temperatures may result in malfunction of the system. ATTENTION: Only qualified personnel familiar with the PowerFlex 700S AC Drive and associated machinery should plan or implement the installation, start-up and subsequent maintenance of the system. Failure to comply may result in personal injury and/or equipment damage. ATTENTION: To avoid an electric shock hazard, verify that the voltage on the bus capacitors has discharged before performing any work on the drive. Measure the DC bus voltage at the +DC & DC terminals of the Power Terminal Block (refer to Chapter 1 in the PowerFlex 700S User Manual for location). The voltage must be zero. ATTENTION: Risk of injury or equipment damage exists. DPI or SCANport host products must not be directly connected together via 1202 cables. Unpredictable behavior can result if two or more devices are connected in this manner. ATTENTION: Risk of injury or equipment damage exists. Parameters 365 [Encdr0 Loss Cnfg] [VoltFdbkLossCnfg] let you determine the action of the drive in response to operating anomalies. Precautions should be taken to ensure that the settings of these parameters do not create hazards of injury or equipment damage. ATTENTION: Risk of injury or equipment damage exists. Parameters 383 [SL CommLoss Data] [NetLoss DPI Cnfg] let you determine the action of the drive if communications are disrupted. You can set these parameters so the drive continues to run. Precautions should be taken to ensure the settings of these parameters do not create hazards of injury or equipment damage. PFLEX-AP002A-EN-E.doc Page 2 of 8

3 The SLC and PLC-5 do not have a 32 bit integer data type. Therefore, 32 bit integer parameters that come from a drive into the SLC or PLC-5 remain split as (2) 16 bit integers. There are some considerations that should be taken when adding a drive with 32 bit integer parameters to a SLC or PLC-5 system. Drives that are based on 32 bit integer parameters include the PowerFlex700VC and the PowerFlex 700S. Note that the PowerFlex 700S also has floating point parameters. For information on handling floating point parameters over a network please see the PowerFlex 700S Reference Manual. For bitwise parameters, such as Drive Status, there is not an issue when the 32 bit integer remains split as (2) 16 bit integers. This is because we are normally concerned with looking at individual bits. However, for 32 bit integer parameters where we need to interpret the entire decimal value, it can be difficult to interpret the decimal value correctly. The following is a summary of how the decimal values of 32 bit parameters appear in a 16 bit processor: 1. If the value of the data is less than decimal and it is a positive value, the least significant word reflects accurate parameter data. In other words, if it is known that the parameter value (taking into account the scale factor) is less than and is a positive value, the parameter can be interpreted easily in the SLC by looking at the least significant 16 bit integer. For example, parameter 414 [Enc Pos Feedback] in a PowerFlex700VC contains a value of Parameter 414 [Enc Pos Feedback] is sent to a SLC over DeviceNet using Datalink A1 Out. The same value appears in the SLC at address I:1.3 which is the lower 16 bit integer of Encoder Position. PFLEX-AP002A-EN-E.doc Page 3 of 8

4 If we look at the data in binary format we can see that there are no bits on in I:1.4, which is the upper 16 bit Integer of Encoder Position. 2. If the value is greater than 32767, bits in the most significant 16 bit integer will be on. Therefore, it is not sufficient to look only at the least significant integer. Since there is no double integer data structure in the SLC or PLC-5, it is difficult to interpret the entire 32 bit data. For example, parameter 414 [Enc Pos Feedback] in a PowerFlex700VC contains a value of PFLEX-AP002A-EN-E.doc Page 4 of 8

5 If we look at the corresponding values in the SLC, it seems that neither the lower 16 bit integer or the upper 16 bit integer correspond to the value In fact, the lower 16 bit integer is a negative value. When the data is seen in binary format, we see that there are bits on in both the upper and lower integers, I:1.3 and I:1.4, indicating that the value is larger than If the value is negative (less than 0), bit 15 in the upper 16 bit integer will be 1. When the value of the parameter is between 0 and , it is possible to look at just the lower 16 bit integer value. PFLEX-AP002A-EN-E.doc Page 5 of 8

6 For example, parameter 24 [Commanded Torque] is -5.1%. This corresponds to an internal value of -51 when the scale factor is taken into account. -51 is what is sent through the communication adapter. Parameter 24 [Commanded Torque] is sent to a SLC over DeviceNet using Datalink A1 Out. We can see that the lower 16 bit integer value of -51 corresponds to the value of -51 in parameter 24. The upper 16 bit integer will be -1 when the value of the parameter is between 0 and In binary we can see that the upper 16 bits are all 1 when the value of the parameter is between 0 and PFLEX-AP002A-EN-E.doc Page 6 of 8

7 4. When the value is negative (less than 0), but beyond the range of 0 to , the upper 16 bits will again change. It will not be sufficient to look at just the lower 16 bit integer. For example, parameter 414 [Enc Pos Feedback] in a PowerFlex700VC contains a value of If we look at the corresponding values in the SLC, it seems that neither the lower 16 bit integer or the upper 16 bit integer correspond to the value In fact, the lower 16 bit integer is a positive value. PFLEX-AP002A-EN-E.doc Page 7 of 8

8 When the data is seen in binary format, we see that bit 15 is on in the upper 16 bit integer, I:1.4, indicating that the parameter value is negative. PFLEX-AP002A-EN-E.doc Page 8 of 8