OK4U Data Acquisition
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| There are a variety of ways to obtain data from the OK4U. However, it has been difficult to obtain documentation and software specific to the OK4U, probably due to its lack of current UL approval. This page attempts to provide a central location for documentation and resources. Documentation and software on this page is provided for informational purposes only and it is incumbent upon the reader to install and configure any grid tied inverters in a safe and responsible manner.
How do you interface with the OK4 inverter?The OK4 series inverters use a two wire, half duplex RS485 protocol. If you are unfamiliar with this protocol, which is commonly used in industrial automation, here is some excellent background reading:http://rs485.bb-elec.com/rs485.htm The RS485 protocol is common on industrial Single Board Computers and Programmable Logic Controllers. It can also be used via the serial port of a PC, with a RS232 to RS485 adapter. NKF sells a proprietary adapter, the OK485 which can interface with up to 128 inverters, up from the standard limit of 32 devices. Do I have to use a NKF OK485 adapter?No, but it is a good idea to use an optically isolated adapter if you choose not to use the OK485. The following document details the differences of the OK485 protocol from the standard RS485 protocol: I have had success with using a IC-485S which also comes in an optically isolated version, the IC-485IS. Also, here is a link to someone who built their own adapter: What platforms can communicate with the OK4U?Windows NKF distributes software that runs in a Windows environment. It is written by a third party and appears to have no active development. My experiences with the NKF Windows applications have been mixed. Supervisory functions are disabled unless you have a key from NKF. They appear to be (understandably) worried about safety and liability. DOS This application was once distributed by Trace with the MS100 and works with the OK4U. It can change the inverter control parameters (be careful) but cannot output data to a file. Do not use the 'Restore Default Values' option. For your safety reason, I will need for you to email me with a short description of your project and why you need the application. I will then send you the password for the archive. Also, if you want to run this application on a computer with a fast (>200 MHz) processor, you may need to use this utility to avoid run time errors. Unix There is one application I know of that runs on a Linux or Unix platform. I assume it will work on a Mac with only minor modifications. It is written for the OK4E by an individual from Holland. I have modified this application to work for US inverters and can send you the application and source code upon request. Other Here is a link to a Dutch site that has an application written which replaces the firmware on the OK4E. I would use this with extreme caution on an OK4U: How does the OK4U differ from the OK4E?There primary differences are their grid voltages and frequencies. The OK4U is designed for use on the US grid which has an AC voltage of 115 and frequency of 60 Hz, while the OK4E is designed for the European grid and operates using an AC voltage of 230 and with a 50Hz frequency. Because the baud rate used for communication with the inverter is linked to the grid frequency, the OK4U requires a speed of 360 baud as opposed to the the speed of 300 baud which is used by the OK4E. This may seem to be a trivial difference, it presents a more significant challenge when writing an application. That is because 360 baud is a non-standard rate and typically does not have a reserved UART entry. Other Useful Things:Inverter database reader utility (for use with NKF's OK4 Manager application) SP12 parallel programmer software (for loading firmware such as Invermate - http://www.xs4all.nl/~sbolt/e-spider_prog.html) Cavaj java decompiler (for rebuilding java source code from compiled JAR files) Worldlingo Translator (Dutch to English translation)
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