Hands-on Modbus Cloud Connect – Retrofit remote meter reading via S0 / pulse interface

Viktor Deyemanns

Viktor Deyemanns – Business Development Engineer

Hands-on Modbus Cloud Connect – Retrofit remote meter reading via S0 / pulse interface

Remote meter reading via the pulse interface

Close-meshed consumption data recording is essential for identifying consumption and taking savings measures. Regular meter readings for consumption analysis, e.g. every 15 minutes, are only possible through a connected metering system. Ideally, this is designed with appropriate interfaces, but this is not always the case.

About the blog article series:
Modbus is a data communications protocol and has become a de facto standard protocol to connect industrial electronic devices. But how could those devices become part of the internet of things and what use cases could be developed? With this series of blog articles, we would like to give answers, ideas, suggestions, and helpful hints. To demonstrate how easy, it is to bridge the gap between devices and IT/cloud infrastructure by using Modbus Cloud Connect.

Many older metering devices (electricity, gas, water, heat, etc.) initially give the impression that they cannot be connected. Especially if they are mechanical meters. However, it is usually possible to connect even these analog meters via additional hardware. These are typically the manufacturer’s own adapters with a pulse or S0 interface. In this blog article, we describe how an analog measuring device can be connected with Modbus Cloud Connect.

The application can be useful wherever there are different tapping points with mechanical measuring devices. Modernization of the measuring system is not always considered or worthwhile. For example, in larger properties or industrial parks, there are many metering devices in order to determine the energy consumption for each individual consumer. Connectivity of the meters replaces the manual meter reading process and creates sufficient transparency of consumption in the context of energy saving.

Information:

Pulse interface: An electrical pulse generator emits pulse signals, e.g. in the form of voltage pulses via a relay or switch. In the context of consumption measurement, the pulse generator of a measuring device generates pulses that are proportional to consumption, e.g. 100 pulses/kWh. Electrical pulse generators are not subject to any standard, so the pulse generator must be compatible with the electrical specifications of the pulse meter (pulse duration, voltage, current, etc.).

S0 interface: An S0 pulse generator is subject to the EN 62053-31 standard. The voltages and currents are defined in classes here so that compatibility between the generator and meter is ensured. In addition, there is a continuous offset signal on the line so that a low signal can be distinguished from a line interruption.

The measuring device initially requires a pulse or S0 interface. If this is not available, it may be possible to retrofit it as an accessory to the meter model. These are usually adapters that are mounted on the meter. The adapters recognize the activity of the meter clock and generate corresponding pulses per consumption unit. It is not possible to read out the absolute meter reading digitally via the interface. However, the pulses can be counted so that a meter reading can be generated separately from the measuring device.

Example of a gas meter with a mechanical meter mechanism. The manufacturer offers a compatible sensor with pulse interface for the model

Impulse counter

The Honeywell EEM-Convert is a module with 4 pulse/S0 inputs. The module manages four meter readings that are incremented via the pulse inputs. The values of the counter readings can be written via the Modbus interface in order to adapt them to the value of the measuring device. It is also possible to specify how many counting units are incremented per pulse. The module can thus maintain an identical counter reading parallel to the reading of the measuring device. Up to four measuring devices can be connected. The type of metering device (water, gas, electricity, etc.) is irrelevant here. All that is required is an interface.

Hardware setup on the top-hat rail: Honeywell EEM Convert, power supply unit, Modbus Cloud Connect

Modbus Cloud Connect

Modbus Cloud Connect reads the meter readings via the Modbus RTU interface and transmits them via NB-IoT or LTE-M, depending on availability. Configuration is conveniently carried out remotely via the self-service portal. The meter readings are then transmitted to any end point via HTTP or MQTT.

End-to-end - components for digital remote reading of metering devices

Connected end-to-end with ease

With the appropriate additional hardware, many types of meters can be connected and a digital infrastructure created to provide transparency in energy consumption. The above-mentioned hardware components form a transmission path that provides the meter reading for a platform. This can be a visualization platform from our partners Device Insight or Datacake, for example. This combination of all components represents the entire end-to-end infrastructure for realizing the use case.

Example of an individual dashboard for displaying consumption data at a point of use Modbus Cloud Connect makes it easy to use, flexibly connectable and broadly applicable. Your device, directly to the cloud.