7/8/2010 5:26 PM | |
Posts: 6 Rating: (0) |
Hello I use a pressure transmitter 0-25 Bar on the AI1 of a logo 12/24RC. My signal is a 4-20mA an I always get only the maximal pressure as result If I look into the logo, I get AI1 : 1000 After reading and re-reading the documentation I have first a simple question : is my logo able to read this 4-20 mA aor do I need to convert it into 0-10 V ? My pressure transmitter is actually connected in L+ and in I7. Here the pressure transmitter's documention :http://docs-europe.origin.electrocomponents.com/webdocs/0114/0900766b80114317.pdf Thanks in advance |
Last edited by: tempo0512 at: 7/8/2010 5:46 PM |
|
7/8/2010 6:15 PM | |
Joined: 9/6/2008 Last visit: 3/29/2024 Posts: 134 Rating: (16) |
the logo which you have is able to read analog 0-10V. but you may use a " curent loop " for to get readings 0-20ma=0-10v http://www.bapihvac.com/CatalogPDFs/I_App_Notes/Current_Loop_Configs.pdf http://www.bapihvac.com/CatalogPDFs/I_App_Notes/Designing_Current_Loops.pdf a few more info about curent loops AttachmentUnderstanding_Current_Loops.pdf (718 Downloads) |
Last edited by: cdrshort at: 7/10/2010 7:39 PMhttp://electrotech-techblogg.blogspot.gr/ |
|
7/8/2010 10:08 PM | |
Posts: 6 Rating: (0) |
Thank you. I try this as soon as i get the resistance. |
7/9/2010 7:29 AM | |
Posts: 21 Rating: (1) |
Use a resistor. I use on my logo 12/24 a ntc temp sensor 4-20 with resistor 6K and its ok. On the forum you can find more info. |
7/9/2010 10:32 AM | |
Posts: 173 Rating: (95) |
Hey cdrshort! THANKS! great bit of info you attached. I wrote at length about this topic some time back (cannot find the link right now). So, if the LOGO! can quite easily read a 0..10 VDC signal, then if an EXTERNAL precision resistor is used, then this is actually the same as Rreceiver (in the documentation)! WOW! I never knew this! I was always taught that current loops do not like more than 250 ohms in the loop - now I know what is actually meant! Attached are some readily available high precision resistors that can be used successfully! Hope it helps someone! Cheers Aaaaarrrggghhh!!! ("Have a nice day!") Attachment4-20mA_and_Resistors.zip (1145 Downloads) |
This contribution was helpful to1 thankful Users |
7/9/2010 9:21 PM | |
Joined: 12/27/2006 Last visit: 8/18/2024 Posts: 1197 Rating: (113) |
Siemens have make a mistake in the doc 4-20mA_and_Resistors.zip The resistor of 500 Ohms must be min. a 0,25 Watt type. P= I x I x R I= max 20 mA (Currend loop) 0,02 x 0,02 x 500 = 0,2 Watt Use a 0,25 Watt type , bettre a 0,5 Watt type is good |
This contribution was helpful to1 thankful Users |
Follow us on