Generating a Pulse output from a known Frequency value

jcampbell79

Member
Join Date
Nov 2017
Location
Woodstock, IL
Posts
3
The RPM of the motor can be accurately scaled to the RPM of the gearbox output. If I can in the PLC code generate a boolean output pulse with the same frequency then my SCADA program can read that over the network instead of the prox it is currently looking for.

Currently it is counting pulses from a Prox switch but due to the nature of the machine something on a semi regular basis either damages the prox or the bolt it is sensing. I have in my PLC communication to a VFD drive that is controlling the motor driving the Gearbox with an encoder feedback for precise control.
 
I believe you are trying to 'fix' the wrong thing. The SCADA is detecting the state of the system downstream from the VFD/motor. Thus it is sensing a failure of any component in between them and the bolt/prox combination. Your suggestion would bypass this detection. By the way the bolt/prox problem may be pointing to a bearing or support failure for the rotating component to which the bolt is attached.
 
I believe you are trying to 'fix' the wrong thing. The SCADA is detecting the state of the system downstream from the VFD/motor. Thus it is sensing a failure of any component in between them and the bolt/prox combination. Your suggestion would bypass this detection. By the way the bolt/prox problem may be pointing to a bearing or support failure for the rotating component to which the bolt is attached.

Bernie,

I may have misspoke when I said SCADA it is actually a data acquisition program that is totalizing volume of product used by counting revolutions. The bolt was put there to see the shaft rotate and has no other function. I would like to eliminate the prox switch as the information already exists but just in a different form. I need to convert the signal to a usable value.
 
I would base the calculated pulses off of the encoder feedback if that is available in your PLC as opposed to expected frequency based on the VFD command signal.

But in any case, you're going to have to tell us a lot more about the hardware you are dealing with to get any specific advice.
 
hardware / process description.

I would base the calculated pulses off of the encoder feedback if that is available in your PLC as opposed to expected frequency based on the VFD command signal.

But in any case, you're going to have to tell us a lot more about the hardware you are dealing with to get any specific advice.

I have a VFD driven melt pump on a plastic extrusion machine. One revolution of the pump is equal to x lbs of material. We use IQMS software to keep track of our inventory and efficiency.

The melt pump is driven by a gear box with a motor on a VFD. The VFD has encoder feed back to maintain a set speed by the process. This speed is scaled for the gear ratio of the gear box so that the operators input the RPM they want the melt pump to turn at.

Currently there is a prox switch that is reporting one pulse per revolution directly into the IQMS server. This prox is sensing a bolt head that had been placed into the shaft between the gear box and the pump. Due to the dirty nature of the process and occasional leaks of the plastic from the seals of the pump the bolt or the prox switch gets fouled up and damaged. This is why I'm looking for a code solution to this. In my AB L61 processor I have control net communication to the PowerFlex 700 Vector Drive.

I can obtain either the RPM of the motor or the scaled RPM of the pump. I would like to use these values to generate a simulated pulse bit that I can then communicate via the network into the IQMS software via a Kepware interface.
 
I have a VFD driven melt pump on a plastic extrusion machine. One revolution of the pump is equal to x lbs of material. We use IQMS software to keep track of our inventory and efficiency.

The melt pump is driven by a gear box with a motor on a VFD. The VFD has encoder feed back to maintain a set speed by the process. This speed is scaled for the gear ratio of the gear box so that the operators input the RPM they want the melt pump to turn at.

Currently there is a prox switch that is reporting one pulse per revolution directly into the IQMS server. This prox is sensing a bolt head that had been placed into the shaft between the gear box and the pump. Due to the dirty nature of the process and occasional leaks of the plastic from the seals of the pump the bolt or the prox switch gets fouled up and damaged. This is why I'm looking for a code solution to this. In my AB L61 processor I have control net communication to the PowerFlex 700 Vector Drive.

I can obtain either the RPM of the motor or the scaled RPM of the pump. I would like to use these values to generate a simulated pulse bit that I can then communicate via the network into the IQMS software via a Kepware interface.

If you calculate your frequency over a period of 1 second, you can determine the output pulse train as how many 0.1 second intervals between the change of state of the output boolean. A scheduled task at 100 ms can then decrement the preset value and toggle the output bit you send to the 'SCADA' system.

The boolean can drive an actual output or be communicated with the Scada system.

This is approximately how our natural gas vendor sends us pulses to totalize for usage, and how our power vendor used to (and still can) send us pulses for kw-h and kva-h. The vendors use RTU's to perform the task. They are quite accurate - the natural gar RTU has dedicated AGA7 flow calculations, a calibrated flow meter, etc with temp and pressure compensation. The power RTU has expensive CTs and PTs for calculating phase, measuring current, etc.
 

Similar Topics

Hi! First time posting here. New to AB PLC family and working on this new project. Using Micro850 PLC and PV800 HMI and CCW. The project is to...
Replies
1
Views
1,420
Im using studio 5000, in my software, Im using E300 overload protection relay to control a motor. Studio 5000 Version 32.12 E300 Version 7...
Replies
5
Views
2,795
Hi, I have a new PCS7 project with a 6ES7 417-4XT07-0AB0 CPU. When compiling the System/module CFCs are generated from the hardware. But in my...
Replies
1
Views
1,243
Hello Guys, I spent some time searching the web to learn how to generate the report (to be printed out or to be saved as pdf file) which would...
Replies
0
Views
1,187
Hey all, I'm trying to use a OB16IEF to generate a 24V PWM signal. According to the manual all i have to do is set... Local:#:C.Pt[#].PWMEnable...
Replies
7
Views
2,891
Back
Top Bottom