Hello thammu,

Your descriptions are a little confusing. And your program doesn't really fit in either. That's why I have a few questions:

Do you want to cool down one room with two cooling systems ?

Does each cooling device have its own control unit, each with two temperature sensors (That would be four sensors.) ?

Or should the sensors be used to measure the temperature of the room (which makes more sense) ? Then you only need one sensor ! (You could also provide a fail-safe for the sensors. Three sensors would then be required - but that is a separate topic).

What about the overheating protection of the compressors ?

Should the standby compressor be switched on at temperatures above 30°C ? (Changing wouldn't work. Because this compressor would not have cooled when switching over and would trigger another switchover.)

You have to explain the digital inputs I3 to I6 in more detail, because I can't follow you.

Greetings Ella_68

hi good evening, 

the program i attached is only just for weekly and trip changeover.i know it doesn't match with my requirement. but i need to modify with an analog input.

i need to cool down one big room with one cooling system. but i have installed two cooling systems for the same room for duty(unit A) and stby(unit B) option.when duty one gets tripped then it will change over to the stby unit and vice versa,when reset has been done.also there will be a weekly change over, unit A will run for 7 days after completing the run hours it will automatically change over to unit B.

the cooling system had temp control earlier with some controller which got problem. now i am planning to modify with logo.earlier it was having one temp temp sensor for each cooling system.

i have seperate overload/ over heat protection of compressors. in case of any trip it will give signal to logo. Di 5 for unit A,Di 6 for unit B.

if the main room temperature reaches 30 c or above, the running unit should stop and a change over should happen.

DI 3 and DI 4 are the auto/ manual input selection in panel, in auto there should be trip,weekly change over. in manual the selected unit should run continous without any change over.

i hope this may be helpful. thanks .

hello thammu,

Although something is still unclear (it could also be the translation from Google), I programmed something based on your descriptions.

Maybe it will help you.

Greetings Ella_68

hi Ella_68

the file is not opening.its showing error. pls help.

thank you so much for your support .i still have some doubts.

when the temperature of the room increases 1.5 C from the setpoint 23 C stage 1 is active. ok

when temp still raises above 24.5 C stage 2 is active. ok

while the temperature starts to drop down below 24.5 C but still did not achieve the stpt temp 23 C, stage 2 should be deactivated and only stage 1 should be active until reaching the stpt 23C.

23 to 24.5 stage 1 run,stage 2 off

24.5 to 30 stage 1 run,stage 2 run

30 to 24.5 stage 1 run,stage 2 run

24.5 to 23 stage 1 run,stage 2 off

pls suggest me the logo model and ext module for this project.

hi good evening,

 i need sample program for trip change over between those two cooling units.when unit A trips it should changer over to unit B,and vice versa.TIA.

Hello thammu,

You determine how and when switching occurs with the analog threshold switches B006 and B007. Set the parameter connections as you need them. The switchover in the event of an error is already implemented. The inputs I5 and I6 are intended for this. If one unit fails (input = 0), it switches to the remaining one. In the appendix is another example with a different switching sequence for B006 and B007.

Greetings Ella_68

Ups, Sorry, forgot the program

hi  good evening, 

Thank you for the update. 

when the temp rasises above 30c both the coolers are getting on. pls can you check. the last program was working fine with the high temp change over

currently i am having 230 rce model. pls can you suggest me for an upgradation for using analog input temp sensor. and extension module for this program

also can you give me a reset input,a momentry push button, to reset the trip from comp high temp.because program is in stop when trip occurs in any input i5,i6. i have attached the screenshot,when it stops. for your ref.