If you are one of the few manufacturers who already has a digital panel meter in place, you may already have Modbus communications capability and just not realize it. A sizable percentage of digital power meters have this capability
First, check your meter’s data sheet to make sure it has Modbus capability. There are two typical types:
- Meters that use ethernet connections for connecting directly into the network.
- Meters with Modbus RTU that use RS495 serial connections. A converter device may be required for this type to connect to your network.
If you’re currently using analog meters, you’ll need to choose a digital meter with Modbus communications. There are several considerations for choosing the right meter that will make the process significantly easier.
1) Ease of Integration
Make sure you find a meter that will fit into your existing panel to minimize the re-work of your product. Power meters come in a variety of sizes. ¼ DIN (96mm x 96mm) is very common but there are some that are larger and some that are smaller. If you are using analog meters with a 3 position switch you likely have all the panel space you need. With the diversity of panel openings on power meters currently available on the market, reworking your panel may be avoidable.
2) Environmental Certifications
Depending on the typical environment where your generators are used, you’ll want to find a meter with the appropriate certifications. If outdoor use is expected, then make sure you select something with a NEMA4 rating at a minimum. Also be conscious of temperature considerations. Some meters handle low temperatures better than others. UL, CE and other agency approvals are also important, although every digital meter should carry the appropriate approvals.
3) Ease of Configuration
There are two elements to configuration: the configuration of the meter itself and the configuration of the communication network to read the data from the meter.
The configuration of the meter will be unique to the generator it’s being installed on. This will involve things like maximum voltage, the parameters that are to be monitored and the values of the current transformer. Meters that have free configuration software are generally the easiest to set up.
The configuration of the network to read the data should be very similar for all manufacturers since all manufacturers that offer Modbus follow the Modbus protocol. Once the data is in your network, then it is completely up to the user to decide what to do with it.
4) Other Considerations
- Lock Out Feature: If the generator will be accessible to people other than the authorized operator, you may want to make sure your meter has a lock out feature to avoid tampering so the data sent to the network is correct.
- Current Transformers: Most digital power meters will be limited to accepting up to 5 amps directly. For current values over 5 amps, external current transformers will be required.
- Potential Transformers: Most 3 phase generators operate in the neighborhood of 480 volts; however, some will be higher. Typical digital power meters are limited to 600VAC, so potential transformers will be required for voltages higher than 600.
Meters with Communications Capabilities at Trumeter
Trumeter’s Vista Touch digital panel meters come standard with a Modbus port that can be used for two-way communication with any other Modbus-capable master device. This line of meters also has built-in connectivity to Trumeter Cloud for remote monitoring, custom alarms and the ability to collect and analyze data over time.
Trumeter’s Advanced Panel Meters can be customized with Modbus capabilities, and can easily be connected to Trumeter Cloud with the APM Gateway for remote monitoring capabilities.
