Kkula
Browse Questions » LOGO! - Projects: Serious Continuous Signal Coding issues

About User

Amit Pandey

Questions Asked: 36.7K

Answers Given: 0

Statistics

Tags

0
  • Open
  • New
Amit Pandey
Asked:15 Jan 2026

LOGO! - Projects: Serious Continuous Signal Coding issues

Hi, everybody.
It has been around 13 years since I last did some programming of PLC´s. So my knowledge is very rusted and the analog programming is giving me nightmares 
I want to control my aquarium.
Programming simple DI and DO for the filter, thermostat and powerhead is done, but I also need to ramp up voltage output (0-10V) over a period of 40ish minutes. When it reaches 10V it needs to stay that way for 7 hours and then ramp down again to 0 V (also 40ish minutes).
This needs to happen on two different outputs. But one is inverted.
I.e:
Analog out1: Starts ramping up at 13:20. At 14:00 it hits 10V and stays there until 21:00. At 21:00 it starts ramping down, hitting 0V at 21:40.
Analog out 2: Starts ramping up at 21:00, hits 10V at 21:40 and stays there until 13:20. Then it ramps down again, reaching 0V at 14:00.
I also need to program a pH-electrode analog input to turn my CO2 supply on/off.
I have the following mdoules:
Logo 12/24RCE
1 DM8 12/24R
1 AM2 AQ
1 AM2 RTD
Totally lost here as a newbie and would be so grateful, if anyone could help me out. I have watched a few youtube videos, but didn´t get any closer to it. Maybe I´m just stupid  
Maybe this should have been posted in Projects. If so, could a Mod please move it ?

#sosflex #LOGO! - Projects #siemens
1Answers 2Views 0Votes
0 Likes 0 Favourites 0 Followers 0 Comments
Answers(1)
Deleted Member Added an Answer on17 Jan 2026

Aquarium Control with LOGO! 8 - Analog Output Ramp Up/Down

Hello! It's great you're revisiting PLC programming. Don't worry about feeling rusty – we can help you with your aquarium control project using your LOGO! 8 and modules.

Here's a breakdown of how to approach this, focusing on the analog output ramp up/down functionality:

Analog Output Control (0-10V)

  1. Ramp Up/Down Blocks: LOGO! 8 has dedicated analog ramp up/down blocks. These are your primary tools. You'll configure them with a start trigger, ramp time (40 minutes), target value (10V), and hold time (7 hours = 420 minutes).
  2. Two Outputs: Implement two separate ramp up/down chains – one for 'Analog Out1' and another for 'Analog Out2'.
  3. Inverted Output: Use a NOT block before the 'Analog Out2' ramp up/down chain to invert the signal as required. This will effectively reverse the behavior.
  4. Time-Based Triggering: Use the LOGO! 8’s time functions (TON – On-Delay Timer) to trigger the start of each ramp up sequence at 13:20 for Output 1 and 21:00 for Output 2. Ensure these timers are enabled for continuous operation.
  5. Sequencing: Carefully consider the logic to ensure smooth transitions between ramping up, holding, and ramping down. Use interlocking logic to prevent conflicting commands.

pH Electrode Input & CO2 Control

For the pH electrode (AM2 AQ), use the analog input block. Configure a comparison block (e.g., greater than/less than) to set a threshold pH value. The output of the comparison block will directly control the CO2 supply (via a DO – Digital Output).

Resources

Tip: Start with a simplified version controlling just one output. Once that works, expand it to include the second output and the pH control. Break down the problem into smaller, manageable steps.

0
Add a comment