The PRO EX digital panel meter from LOGGON TECH is a modular instrument for measuring, displaying and retransmitting electrical parameters in industrial switchgear and control panels. One unit integrates a digital display, analog output, RS485 communication, over-limit alarm recording and relay output, so a single device covers local indication, remote signalling and alarm functions. Decimal point and unit switching are automatic, and the CT ratio, PT ratio, communication address, baud rate and upper/lower alarm values are programmable. The meter is built with a high-brightness LED display and an anti-surge design. Documentation references GB/T13978-1992, GB/T13850-1998, GB/T17620.X-1999, IEC1010 and EN61010.
Digital panel meter overview and where it is used
A digital panel meter converts a measured electrical quantity, such as current, voltage or power, into a numeric reading on a local display and, in most industrial installations, into one or more output signals for a control system. In switchgear and plant panels the meter serves three functions: local indication for operators during inspection and switching, alarm generation when a parameter exceeds a set limit, and retransmission of the measured value to a PLC, RTU or energy management system.
The PRO EX is intended for panel mounting in industrial environments where surges and electromagnetic disturbance are present. An anti-surge design is among its documented features, relevant on plant distribution boards fed by motors, contactors and variable-speed drives. Typical installation points include:
- Low-voltage distribution panels, as local indication of current and voltage on incoming and outgoing feeders.
- Motor control centres, where the relay output can drive an alarm or interlock circuit when a set limit is exceeded.
- Machine control cabinets, where the analog output retransmits a measured value to a controller or recorder.
- Sub-metering and monitoring panels, where RS485 communication reports readings to a supervisory system.
- Retrofit projects replacing older analog instruments, subject to mechanical and wiring checks against the existing panel.
Models in this range
PRO EX digital panel meter
The PRO EX is the model in this range. Its modular design combines the following functions in one unit:
- Digital display with a high-brightness LED readout, with automatic decimal point and unit switching.
- Analog output for retransmission of the measured value to a controller, recorder or PLC analog input.
- RS485 communication for connection to a supervisory system or data logger.
- Over-limit alarm recording, so limit events are retained for later review.
- Relay output for switching an external alarm, interlock or annunciator circuit.
Programmable parameters cover the CT ratio and PT ratio for scaling the measured value, the communication address and baud rate, and the upper and lower alarm values. Because scaling and alarm setpoints are set in the meter rather than by hardware links, a change of feeder rating or alarm threshold can be made without replacing the instrument.
On the display technology point: many panel instruments use LCD displays, and an lcd panel meter may suit low-light control desks or low-power installations. The PRO EX uses a high-brightness LED display, which suits panels viewed from a distance or under strong ambient light.
How to select
Selection starts with the measured quantity and range, then moves to the scaling, output and alarm requirements. The following points should be confirmed before ordering:
- Measured parameter: the quantity and full-scale range the meter must display, and whether a CT or PT is in the measurement path.
- CT ratio and PT ratio: both are programmable on the PRO EX, so the meter reading can be scaled to primary values.
- Output functions required: analog retransmission, RS485 communication, relay output, or a combination. The modular design allows the functions actually needed to be specified.
- Alarm requirements: the number of alarm points and the upper and lower limits to be programmed, plus whether over-limit events must be recorded.
- Communication settings: address and baud rate for the RS485 bus.
- Environmental and surge conditions: where surge exposure is a concern, the documented anti-surge design is relevant (the protected circuits follow the model documentation) to the selection.
- Panel space and wiring: confirm the cut-out, terminal arrangement and wiring diagram against the manufacturer's documentation before panel fabrication.
For compliance review, the documentation references GB/T13978-1992, GB/T13850-1998, GB/T17620.X-1999, IEC1010 and EN61010. These references should be checked against the project specification and the applicable documentation supplied with the unit.
Integration and communication
The PRO EX connects to a control system through two paths: the analog output and the RS485 communication port. The analog output is used where a controller or recorder has a spare analog input and a continuous, hard-wired signal is preferred. The RS485 port is used where multiple meters share a bus and readings are collected by a supervisory system; in this case, each meter needs a unique address and a common baud rate, both programmable in the unit.
The relay output can be wired to an alarm annunciator, a lamp, a horn or an interlock input on a PLC. The over-limit alarm recording function retains limit events, which supports later review of trips and excursions. Decimal point and unit switching are automatic, so the displayed value follows the configured scaling without manual adjustment at the panel. During commissioning, verify the CT and PT ratios against the installed transformers, confirm the alarm limits, and test the relay and analog output against the receiving device before the panel is put into service.
FAQ
What functions does the PRO EX integrate?
One unit integrates a digital display, analog output, RS485 communication, over-limit alarm recording and relay output.
Which parameters are programmable?
The CT ratio, PT ratio, communication address, baud rate, and upper and lower alarm values are programmable.
What display does the meter use?
The PRO EX uses a high-brightness LED display with automatic decimal point and unit switching. An lcd panel meter is an alternative display technology used in other instrument types; the PRO EX model listed here is LED-based.
Which standards are referenced in the documentation?
The documentation references GB/T13978-1992, GB/T13850-1998, GB/T17620.X-1999, IEC1010 and EN61010.
For panel builders and plant buyers, the PRO EX digital panel meter is specified by the measured quantity, the required outputs and the alarm scheme. LOGGON TECH supplies the unit with the referenced standards and programmable scaling and communication settings; confirm the panel cut-out, wiring and project compliance requirements against the manufacturer's documentation before installation.