James Mimlitz @ SCADAmetrics – ‘Slim’
Many commercial and industrial flow meters feature a 2-wire, pulse-output that represents a volumetric total signal (eg: gallons). For example: 1 pulse = 1 gallon, or 1 pulse = 10 gallons, etc… The volumetric pulse signal has historically been used by SCADA (Supervisory Control and Data Acquisition) systems to convey totalized flow. Furthermore, the meter’s pulse rate (pulses per minute) can be scaled into a rate-of-flow signal (eg: gallons per minute) to provide a complete metering picture to the SCADA system.
Often, there is a desire to co-connect these same meters to an AMI/AMR system using a 3-wire encoded AMI signal, However, if the meter is not natively outfitted with this signal, then a SCADAmetrics model PTE Pulse Encodalizer can be used to convert the pulse signal into a 3-wire encoded signal.
“But what if the meter’s pulse signal is already being used by the SCADA system?”
If that is the case, then the pulse signal must first be split for sharing. The SCADAmetrics model APK Analog/Pulse Kit is especially suitable for this task, as shown in the following illustration. Note that the Analog/Pulse Kit requires DC mains power (9-36Vdc):
In the above illustration, a pulse output signal from a magnetic flow meter is split and co-connected to both a SCADA system and an AMI system.
For AMI connectivity, the SCADAmetrics model PTE Pulse Encodalizer is leveraged to provide a 3-wire encoded AMI signal for flow meters that otherwise do not feature this necessary signal.
It is important to note that a pulse signal (dry-contact, open-collector, open-drain, etc.) cannot simply be wired in parallel to multiple pulse input devices. Each pulse input device (PTE Pulse Encodalizer, PLC, RTU, etc…) provides a unique DC pullup voltage which can damage other parallel devices. Therefore, an isolated split must be performed using an APK Analog/Pulse Kit or other equivalent device.
The APK Analog/Pulse Kit is especially suitable for pulse splitting, because of the following key features:
- Its 2 Pulse Outputs are Solid-State Relays, which will not wear out mechanically
- Its 2 Pulse Outputs and its Pulse Input are all galvanically isolated from each other
- It provides a user-scalable 4-20mA Rate-of-Flow Output, which is often of interest to SCADA users
Questions?…
Are you interested in learning more about how SCADAmetrics flow instrumentation can be combined with magmeters and other specialty flow meters to co-connect meters to both SCADA and AMI systems? Give us a call!… We’ll be glad to discuss the details!