Hello all,
I have project that I'm working on, a verticle axis wind turbine, my control system is allen bradley SLC500 and RSView32 HMI software.
What I woild like to do is bring the information from your meter in my control system and display on the HMI screen. Where do I begin??
Thanks David
PLC/HMI
Re: PLC/HMI
Hello David,
We are very open to how our users access their meter data, you can either read your meters directly or retrieve your data from the EKM Push system.
The very first place to start if you want to read your meters with your own hardware will be to get a good understanding of the meter RS485 protocol. We have the Omnimeter v.3 and v.4 protocols available at the bottom of this page: http://www.ekmmetering.com/developer-portal
As long as you are able to initiate the proper request (including your meter number) over RS485, the meter will respond with most of the data that it contains. You then just have to parse the data and format it to work with your HMI software. I would also encourage you to take a look at the EKM Dash software "Hex Inspector". We have built this to teach you how we read our meters, and interpret the data that is contained in the response. Do you have RS485 available from your control system hardware?
I would also check out the "Developers Sandbox" section of this forum: http://forum.ekmmetering.com/viewforum.php?f=4
If you have any questions, please let us know.
We are very open to how our users access their meter data, you can either read your meters directly or retrieve your data from the EKM Push system.
The very first place to start if you want to read your meters with your own hardware will be to get a good understanding of the meter RS485 protocol. We have the Omnimeter v.3 and v.4 protocols available at the bottom of this page: http://www.ekmmetering.com/developer-portal
As long as you are able to initiate the proper request (including your meter number) over RS485, the meter will respond with most of the data that it contains. You then just have to parse the data and format it to work with your HMI software. I would also encourage you to take a look at the EKM Dash software "Hex Inspector". We have built this to teach you how we read our meters, and interpret the data that is contained in the response. Do you have RS485 available from your control system hardware?
I would also check out the "Developers Sandbox" section of this forum: http://forum.ekmmetering.com/viewforum.php?f=4
If you have any questions, please let us know.
Re: PLC/HMI
I do not have RS485, but I do have RS232 port on the processor(Allen Bradley 1747 L551) channel 0 which could be used. Channel 0 can be configured for ASCII Port Buffer. Would I need a RS485 to RS232 converter?? Read the following, are these assumptions correct:
It appears that the meter is sending and receiving in Hexadecimal code which is converted to ASCII characters. The EKM Metering Data Format example given is definitely converting 123456 78 ASCII characters to 31 32 33 34 35 36 37 38 Hexadecimal characters.
Example: 123456.78kWh (31 32 33 34 35 36 37 38)
There are 8 ASCII instructions in RSLogix that allows receiving and transmitting ASCII instructions to and from the built-in ASCII Port Buffer (which receives data from the RS485 port). There are also 6 ACSII string manipulations instructions. With these 14 instructions, I should be able to write a PLC program that will extract the meter data that is received over the RS485 cable.
Thanks David
It appears that the meter is sending and receiving in Hexadecimal code which is converted to ASCII characters. The EKM Metering Data Format example given is definitely converting 123456 78 ASCII characters to 31 32 33 34 35 36 37 38 Hexadecimal characters.
Example: 123456.78kWh (31 32 33 34 35 36 37 38)
There are 8 ASCII instructions in RSLogix that allows receiving and transmitting ASCII instructions to and from the built-in ASCII Port Buffer (which receives data from the RS485 port). There are also 6 ACSII string manipulations instructions. With these 14 instructions, I should be able to write a PLC program that will extract the meter data that is received over the RS485 cable.
Thanks David
Re: PLC/HMI
If you have full control over what you can write to your RS232 port then you should be good. I would get an RS232 to RS485 converter like this: http://www.ekmmetering.com/ekm-metering ... erter.html
I would just interpret your meter data as HEX and stay in HEX if you can. ASCII can get confusing when the HEX character is not between 30 and 39 (checksums and other characters) We are always looking and thinking in terms of the communication HEX characters. Just creating the meter request string would be confusing in ASCII (ASCII has unprintable characters). The v.4 meter request Hex string: 2f 3f 30 30 30 33 30 30 30 32 33 35 37 38 30 30 21 0d 0a converts to ASCII: /?00030002357800! (you can see that it is missing some characters, 0d 0a are unprintable. They are line feed and carriage return)
Yes, you are correct that 12345678 in ASCII characters directly translates to 31 32 33 34 35 36 37 38 in Hexadecimal characters. Here is a conversion table: http://www.asciitable.com/
Let us know if you need a hand.
Regards,
I would just interpret your meter data as HEX and stay in HEX if you can. ASCII can get confusing when the HEX character is not between 30 and 39 (checksums and other characters) We are always looking and thinking in terms of the communication HEX characters. Just creating the meter request string would be confusing in ASCII (ASCII has unprintable characters). The v.4 meter request Hex string: 2f 3f 30 30 30 33 30 30 30 32 33 35 37 38 30 30 21 0d 0a converts to ASCII: /?00030002357800! (you can see that it is missing some characters, 0d 0a are unprintable. They are line feed and carriage return)
Yes, you are correct that 12345678 in ASCII characters directly translates to 31 32 33 34 35 36 37 38 in Hexadecimal characters. Here is a conversion table: http://www.asciitable.com/
Let us know if you need a hand.
Regards,
Re: PLC/HMI
Ordered 2 of your converters, so when they arrive I will try to steup the comms. I don't know if this is going to work since the PLC is expecting to see ASCII string. What's the dirrenence betweem read and request??
Thanks David
Thanks David
Re: PLC/HMI
You can think of meter communications as:
Meter Request (this includes the meter number, if you send this, the meter with the given number on the RS485 bus will respond)
Meter Response (this includes the meter number, the meter data, and checksum. In order to "Read" the meter you would use this data)
Close String
For meter settings (setting the CT ratio or controlling relays) it gets a bit more complicated.
Hope this helps.
Meter Request (this includes the meter number, if you send this, the meter with the given number on the RS485 bus will respond)
Meter Response (this includes the meter number, the meter data, and checksum. In order to "Read" the meter you would use this data)
Close String
For meter settings (setting the CT ratio or controlling relays) it gets a bit more complicated.
Hope this helps.