metalhouse

I disconnected everything and they behave

Hey @DAQman thanks for this. I tried unplugging the AC supplies and just checking with the thermocouple and other instruments (not powered) connected. The issue persists! I also tried this after disconnecting the DAQ GND from the terminal block.

So I have a system where I have two DC 24V power supplies powering instruments and solenoid valves separately. The negatives of the power supplies are connected to a common block. Also, the GND on the DAQ is connected to same common block. The earthing of all input AC supplies (powering the DC power supplies) are connected together to a separate single point. We have K-type thermocouples attached to the DAQ. These thermocouples are stainless steel sheathed, and that sheath is insulated from the sensing wires (verified). We noticed that when the thermocouples are not attached to anything on our metallic rig, they work fine (water temperature measured with accuracy), but as soon as we actually install it onto something (or short it to the body of the rig), the reading jumps to a VERY high value. We have tried connecting the ground pins on the DAQ to the thermocouple input channels (100k ohms resistors), but the reading is still adversely affected. It seems that it is a common mode rejection (CMMR) problem but we can't figure how to address this. Guidance would be highly appreciated. I have attached a simple schematic for assistance.

Hello @Fausto Im using DAQami. When I swapped the thermocouple the channel started working fine. I dont understand if the thermocouple is faulty then why is my multimeter reading it correctly?

Hello, Out of 5 thermocouples that I have, 3 of the connected ones are reading temperatures in excess of 500oC whereas they should be reading room temperature. Funnily enough, my multimeter when connected to the terminals where the thermocouples are connected shows me the correct room temperature. Why is the DAQ not reading the temperature correctly?

Hello, I was just wondering if I could manipulate the code on DAQami to use a formula for the counter inputs instead of just cumulating pulses/events because thats of no use to me in real time. Thanks, Talha

@DAQman Thanks so much for your answer! Can you tell me why an external power source might be necessary? I am using the SSR linked below, shouldn't this work directly from the DAQ? https://www.digikey.ca/en/products/detail/sensata-crydom/DR10D10/14834324?utm_adgroup=&utm_source=google&utm_medium=cpc&utm_campaign=PMax Product_Low ROAS Categories&utm_term=&productid=14834324&utm_content=&utm_id=go_cmp-20291741422_adg-_ad-__dev-c_ext-_prd-14834324_sig-CjwKCAjwg8qzBhAoEiwAWagLrJMu0qUiFuCWBmGwdY29HCoZxh_my-nc2dlWNR1gE02iKLAhWmFDbBoCIG4QAvD_BwE&gad_source=1&gclid=CjwKCAjwg8qzBhAoEiwAWagLrJMu0qUiFuCWBmGwdY29HCoZxh_my-nc2dlWNR1gE02iKLAhWmFDbBoCIG4QAvD_BwE&_ga=2.44965792.547091212.1721347019-976374151.1712013935 Best, T.

Hello! I have 2 questions about the wiring for the digital output on the USB-2416-4AO. I have a 5V SSR that needs to actuate a valve (connected to an external 24 VDC power supply) based on a sensor value. As I understand, I need to connect the +5V on the DAQ to the positive input on the SSR and the negative input from the SSR gets connected to the digital input on the DAQ. (Similar thing for the connection to the valve). What I don't understand is, do I also need to connect the +5V with anything else (like the GND on the DAQ, which would mean 2 wires are connected to the same +5V port on the DAQ)? Secondly, since I am using Python, I also want to know what is the thing that I should be coding for to energize or de-energize the valve. For me its a pressure value, but lets say I want to energize the valve after a time delay of 15 seconds, and then de-energize it when the pressure reaches a value X, what do I code for? An example of a code would be highly appreciated! Thanks, T.

Hi @JRys, Would this be able to automate the process as well for actuation of valves?

Thanks!

Hi, I have previously received a USB-2416-4AO from Digilent. Now I am trying to use this to run and collect data from my test rig. The goals are: 1. Energize a solenoid valve to open position through the DI/O port 2. Receive a pressure upper value to de-energize the solenoid valve to closed position holding that pressure 3. Wait for a certain period before energizing the solenoid valve again, and then waiting for a period before repeating the same process again for a certain number of cycles So essentially, I need to automate the process based on a pressure signal, number of time steps and number of cycles to be performed. I also need to automate the counter input to be able to give me event number for the given time step because I am assuming the counter ports of this DAQ would not be able to read a frequency wave directly? Based on this, what software do you recommend? Please keep in mind that this is to be used for a research project at Simon Fraser University, BC, Canada and therefore cost of the product should reflect that. Many thanks, Talha

Hey @JRys, what should I do with the internal pull-up on the scaler?

Hello! I have a question regarding the counter input port on the DAQ. I have a flow sensor connected to a scaler (F5140 scaler, pdf attached) which will then send a pulse output to the DAQ. On the scaler specs, it asks to supply voltage that the DAQ itself would be able to handle. I am guessing a 12V DC would be appropriate here given the counter ports can handle +-15V right? Also for the DAQ's minimum current requirements for actually being able to read a signal from the scaler, there is no information regarding this in the user guide. I would need this value to determine if I can use the internal pull-up resistor on the scaler or I would have to resort to an external one. Is there any internal pull up on the counter ports of the DAQ and would they have to be disabled here? Your help is highly appreciated! MT Flo-tech-F5140-F5141-manual.pdf Flo-Tech-K-scale-factor-datasheet.pdf

Hi @Fausto, Thanks for this. Just to confirm, what ports on the DAQ will I need to use to send an actuating signal to the relay you have shared? Regards, MT

Hi, I am just wondering if automating test cases is possible using the free software package DAQami? I basically have the following requirements: 1. Energize a solenoid valve to open position through the DI/O port 1. Receive a pressure upper to value to de-energize the solenoid valve to closed position holding that pressure 2. Wait for a certain period before energizing the solenoid valve again, and then waiting for a period before repeating the same process again for a certain number of cycles I also want to ask if the DAQami will be able to give me actual pulse values in a time step by subtracting the new totalized value from the previous one? I am assuming that the it wont be able to read the square wave individually? Thanks in advance for the help!