Realtime measurements purpose

[smk]

Hello everyone,

I'm relatively new to PLCs and currently engaged in an R&D project involving multiple sensors for measuring torque, RPM, and other parameters. The project entails around 30 channels, and the ultimate goal is to create a comprehensive system with a database and HMI for monitoring various values in real-time. The critical aspect of this project is achieving precise synchronization among the sensors as we intend to multiply different time series (channels), and any slight mismatch could result in significant errors.

Given these requirements, I would greatly appreciate any suggestions on the optimal selection of hardware, automation tools, communication protocols, database systems, and HMI solutions.
and -> I also winna have tiny comparison... Twin CAT vs Step 7

Thank you in advance for your assistance.

 

[drbitboy]

Synchronization is about time. PLC programming and control is primarily about time.

Depending on the manufacturer and model, PLCs typically scan I/O and operate on a scale of 10⁰ms to 10²ms.

What is the timescale of the required process' synchronization?

 

[busarider29]

Anyone here that knows me knows I'm a Beckhoff guy through-and-through. The project requirements that you have are just a few, of many, reasons why. So you need a real-time bus and you also need precision time-synchronized process data, synchronized perhaps down to <= 100nS, means you need EtherCAT and the 'distributed clocks" mechanism it provides out-of-the-box. You absolutely need that for your application!

It sounds to me like you may also require high-sampling analog I/O. Beckhoff has standard analog I/O that samples as high as 100 ks/S. They also have a vast portfolio of "Measurement I/O" that is part of their ELM series. The ELM series I/O can sample as high as 50 ks/S, but it also has a lot of configurable parameters for precision measurement applications (parameterizable filtering, etc...) that the standard I/O does not have. If those sampling frequencies are still not high enough for your application, you still have options -

1. Take one channel from one analog I/O module and one channel from another identical module and interleave their samples in code. This also requires shifting the distributed clock sync time of one of the analog I/O modules in it's configuration. I have done this with success in order to get 200 ks/S sampling frequency.

2. Get a National Instruments 'NI-9144' EtherCAT chassis and fully integrate their I/O into the Beckhoff I/O tree. National Instruments has analog I/O modules for this chassis that can sample as high as 1Ms/S.

You do not need a low PLC scan time because the Beckhoff I/O that I have described here has "over-sampling" technology. Not all of Beckhoff's I/O has this, so whatever I/O you're exploring, check to see if it has "over-sampling" or not. If it does not have "over-sampling", then your I/O "sampling rate" will only be as fast as your PLC scan rate. The scan time of a TwinCAT PLC task can be set as low as 50µS. I have a few applications here where I've had to set PLC task cycle times as low as 100µS because the analog I/O does not have oversampling tech.

 

[tdoa]

Kinda sounds like you just need a Kistler KiBox, assuming its automotive related, they also have DAQ systems.