Process Monitoring & Displays: A Practical Guide to Industrial Process Indicators and Controllers
A pressure transmitter may be working correctly in the field, but if the operator cannot see the actual process value clearly, the measurement has limited practical value.
The same problem appears with flow, level, temperature and other industrial signals. A sensor measures the process, a transmitter may convert that measurement into an electrical signal, but someone or something still needs to interpret, display or act on that information.
This is where process monitoring and display instruments become important.
Depending on the application, the plant may need a simple digital process indicator, a process indicator with alarm outputs, a large display visible from a distance, or a process controller capable of controlling equipment and communicating with an automation system.
Radical TechMart currently lists the iTherm Fx Series Process Controller, PI Series Process Indicator and PI-JD Series Process Indicators within its iTherm range.
The important question is not which instrument has the most features. It is what the operator, PLC or process actually needs to do with the measurement.
What Is Industrial Process Monitoring?
Industrial process monitoring means converting measurements from field instruments into information that operators and automation systems can use.
A typical measurement chain may look like this:
Sensor or Transmitter → Process Indicator → Alarm / Controller → PLC or SCADA
For example, a pressure transmitter may generate a 4 to 20 mA signal. A process indicator receives that signal, scales it into engineering units and shows the actual pressure on the panel.
The same approach can be used for variables such as:
The value of a process display is not simply that it shows a number. It gives operators an immediate view of what is happening in the process.
In an actual plant, that visibility helps during operation, commissioning, maintenance and troubleshooting.
Process Indicator, Process Controller or Jumbo Display?
These instruments may look similar from the front of a panel, but their jobs are different.
| Requirement | Instrument to Consider | Typical Purpose |
|---|---|---|
| Display a process value | Process Indicator | Local monitoring |
| Display and generate alarms | Process Indicator with alarm outputs | Monitoring plus warning |
| Display signal from different sensor types | Universal Process Indicator | Flexible panel monitoring |
| Control a process automatically | Process Controller | Monitoring plus automatic control |
| Send information to another system | Indicator or Controller with communication | PLC, HMI or SCADA integration |
| Show a value from a long viewing distance | Jumbo Process Indicator | Plant floor or remote visibility |
The correct choice depends on what has to happen after the signal reaches the panel.
When a Digital Process Indicator Is Enough
Many industrial applications only need reliable local indication.
The iTherm PI Series includes models such as PI-44, PI-77, PI-88 and PI-99. Radical TechMart lists several PI variants within the same product family, including standard, U, 2 and X configurations.
According to the iTherm catalogue, the standard PI models are designed for linear process inputs with scaling. The catalogue lists user selectable analog signals including 4 to 20 mA, 0 to 20 mA and 0 to 10 VDC for the relevant configurations, along with a programmable display range.
This makes a process indicator useful when a field transmitter is already producing a standardized industrial signal.
For example, a tank may use a level transmitter with 4 to 20 mA output. The operator does not want to see "12.6 mA." The useful information may be "63% level" or a level value in metres.
The indicator provides that conversion between an electrical signal and an understandable process value.
Why Universal Input Matters
A basic indicator may be sufficient when the input type is already known.
A universal process indicator becomes more useful when a panel builder, OEM or plant wants flexibility.
The iTherm PI-U configurations support universal sensor input and transmitter excitation according to the manufacturer catalogue. Excitation options listed include 5 VDC, 10 VDC, 12 VDC and 24 VDC depending on the configuration.
Transmitter excitation matters because some field devices require an external supply.
Instead of adding a separate power supply for every measurement loop, an indicator with suitable excitation may simplify the installation in certain applications.
The exact voltage, current capability and compatibility should always be confirmed against the selected model and transmitter datasheet.
When Alarm Outputs Become Useful
Displaying a process value is one job.
Acting when that value becomes abnormal is another.
Selected iTherm PI configurations include two independent alarm outputs. The higher PI-X configurations also include retransmission and RS485 communication options according to the manufacturer catalogue.
Consider a pressure monitoring point.
The operator may need to see the current pressure continuously, but the panel may also need an alarm if pressure crosses a high limit.
Similarly, a tank level display may require a high level or low level alarm.
This is where the selection changes from "I need a display" to "I need a display that participates in the control or alarm system."
Before purchasing, confirm whether the alarm is only for annunciation or whether its relay will directly interact with other equipment.
When a Process Controller Makes More Sense
A process indicator primarily tells you what is happening.
A process controller can also decide what should happen next.
The iTherm Fx Series listed by Radical TechMart includes Fx-438, Fx-638, Fx-738, Fx-838 and Fx-938 models.
The manufacturer's catalogue describes the Fx series with universal sensor input, PID and ON/OFF control, digital filtering and zero offset, ramp soak functionality and programmable soak timing.
Depending on configuration, output options include:
The ordering structure also provides options for alarms, RS485 Modbus communication and transmitter excitation.
That makes the Fx family relevant when the application goes beyond simply showing a number.
For example, a process controller may receive a measurement, compare it with a setpoint and regulate an output accordingly.
Where Jumbo Process Displays Fit
Some process values need to be visible without standing directly in front of the control panel.
This can happen in production areas, utility plants, test facilities, process lines or other locations where several operators need to see the same measurement.
The iTherm catalogue identifies PI-JD-2 and PI-JD-4 as Jumbo Display Process Indicators. They use a four digit single row display and are offered in different physical display sizes.
The catalogue's ordering information also provides configuration options for alarm outputs, transmitter excitation, retransmission, RS485 Modbus and display arrangement.
A jumbo display is therefore not simply a larger panel meter.
Its purpose is improved visibility where a normal panel indicator may be too small to read comfortably from the required operating position.
How 4 to 20 mA Fits Into Process Monitoring
The 4 to 20 mA signal is common in industrial instrumentation because many transmitters use it to represent a measured process variable.
Consider a pressure transmitter configured for 0 to 10 bar.
The transmitter converts the measured pressure into a corresponding current signal. The process indicator receives that current and scales it into a readable pressure value.
The operator sees pressure.
The electrical system works with the signal.
That separation is one reason process indicators are useful across many measurement applications rather than being limited to one variable.
The same indicator family may therefore be used with different compatible transmitters when its input and scaling capabilities match the application.
What About Retransmission?
Sometimes the displayed measurement also needs to be sent somewhere else.
For example:
Field Transmitter → Local Process Indicator → PLC or Recorder
A retransmission output allows the indicator to pass a corresponding analog signal onward to another system, depending on the model configuration.
The iTherm PI-X configurations include retransmission capability, while the catalogue also identifies optional RS485 communication.
This can be useful when a plant wants both local visibility and centralized monitoring.
Before selecting retransmission, confirm the required signal type and whether the receiving equipment expects analog communication or digital communication.
RS485 Modbus or Analog Signal?
These are different requirements.
An analog signal such as 4 to 20 mA represents a process value electrically.
RS485 Modbus enables digital communication between compatible devices.
Neither should automatically be considered "better."
For a simple measurement point, a conventional analog signal may be all that is required.
For an automation system where multiple values need to be read by a PLC, HMI or SCADA system, RS485 communication may offer advantages depending on the system architecture.
The iTherm Fx ordering structure and selected PI configurations provide RS485 Modbus options.
The communication requirement should therefore be decided while the panel architecture is being designed, not after the instruments are purchased.
Key Selection Factors for Process Monitoring & Displays
Before choosing a process indicator or controller, confirm these points.
| Selection Factor | What to Check |
|---|---|
| Process variable | Pressure, flow, level, temperature or another measurement |
| Input signal | 4 to 20 mA, 0 to 20 mA, 0 to 10 VDC, RTD, thermocouple or other supported input |
| Display requirement | Local panel display or large remote display |
| Scaling | Required engineering range and display units |
| Alarm requirement | No alarm, one alarm or multiple alarms |
| Control requirement | Display only or automatic process control |
| Output type | Relay, SSR, current or voltage output |
| Transmitter excitation | Whether the field transmitter needs excitation |
| Retransmission | Whether the measured value needs to be sent elsewhere |
| Communication | Standalone operation or RS485 Modbus |
| Panel size | Available panel cutout and installation space |
| Power supply | Match the instrument configuration to the panel supply |
Exact specifications vary by series and model. Final input, output, power supply, communication and excitation requirements should be confirmed from the relevant datasheet before ordering.
Common Applications
Process indicators and controllers can be used wherever a measurable process signal needs to be displayed or controlled.
Common examples include:
The important part is matching the input and output architecture rather than selecting solely by the parameter name.
Common Mistakes to Avoid
Selecting only by display size: A 48 × 48 mm instrument and another 48 × 48 mm instrument can have completely different input and output capabilities.
Assuming every indicator accepts 4 to 20 mA: Input compatibility must be confirmed model by model.
Ignoring scaling: The electrical input and displayed engineering value need to be configured correctly.
Adding alarms without defining their purpose: Decide what should happen when the alarm activates.
Forgetting transmitter power: Check whether the transmitter requires external excitation.
Confusing indication with control: A display instrument and a process controller perform different jobs.
Leaving communication until the end: If PLC or SCADA integration is required, decide that during instrument selection.
Ignoring viewing distance: A standard panel indicator may not be suitable when operators need to see the measurement from across the production area.
Do This, Not That
| Do This | Not This |
|---|---|
| Start with the field signal | Start with a product model |
| Confirm the required engineering display range | Assume factory scaling will match the application |
| Decide whether alarms are required | Add outputs without a defined function |
| Check transmitter excitation requirements | Assume every transmitter is self powered |
| Plan PLC or SCADA communication early | Add communication after panel fabrication |
| Use a jumbo display when viewing distance requires it | Use a standard panel meter for distant viewing |
| Match the controller to the control philosophy | Choose the product only because it has more features |
Quick Selection Checklist
Before selecting a process monitoring instrument, confirm:
- What process parameter needs to be monitored?
- What signal comes from the field instrument?
- What engineering range should be displayed?
- Is local indication sufficient?
- Are alarm outputs required?
- Does the application require automatic control?
- Is transmitter excitation needed?
- Is retransmission required?
- Does the instrument need to communicate with PLC, HMI or SCADA?
- Is RS485 Modbus required?
- What panel size is available?
- What supply voltage is available?
- Does the value need to be readable from a distance?
- Has the final model configuration been checked against the manufacturer's datasheet?
Why Buy Process Monitoring Instruments from Radical TechMart?
Radical TechMart lists iTherm's Fx Series process controllers, PI Series process indicators and PI-JD display products within its industrial instrumentation range.
The selection should begin with the application rather than only the product name.
A requirement such as "process indicator required" is incomplete until the input signal, display range, alarms, transmitter excitation, communication, panel size and power supply are known.
At Radical TechMart, the objective is to help customers identify the instrument configuration that matches the measurement and automation requirement before the final product is selected.
Final Thoughts
Industrial process monitoring is about making field measurements useful.
A transmitter may produce the signal, but the process indicator makes that value understandable to an operator. Alarm outputs can highlight abnormal conditions. Retransmission can pass the measurement to another device. RS485 can connect the instrument to a larger automation system. A process controller can go one step further and act on the measured value.
The right instrument therefore depends on three questions:
What signal is coming in?
What information needs to be displayed?
What needs to happen with that information afterward?
Once those three questions are clear, selecting between a process indicator, process controller or jumbo display becomes much easier.
FAQs
1. What is a process indicator?
A process indicator is an industrial panel instrument used to receive and display measurements from compatible sensors or transmitters. Depending on the model, it may accept analog signals such as 4 to 20 mA or 0 to 10 VDC.
2. What is the difference between a process indicator and a process controller?
A process indicator primarily monitors and displays the measured value. A process controller can also compare the measurement with a setpoint and operate outputs to control the process.
3. Can an iTherm PI Series indicator accept 4 to 20 mA input?
The iTherm catalogue lists 4 to 20 mA, 0 to 20 mA and 0 to 10 VDC inputs for relevant PI configurations. The exact selected model should be checked before ordering.
4. What is transmitter excitation?
Transmitter excitation provides a supply voltage that can power a compatible field transmitter. Selected iTherm PI configurations offer excitation options depending on model and ordering code.
5. When should I use a jumbo process indicator?
A jumbo process indicator is useful when the process value needs to be visible from a greater distance than a normal panel instrument allows.
6. Can iTherm process instruments communicate with a PLC or SCADA system?
Selected PI and Fx configurations provide RS485 Modbus communication options. Compatibility with the PLC, HMI or SCADA system should be checked before final selection.
7. Do all process indicators have alarm outputs?
No. Alarm availability varies by model and configuration. Selected PI variants include two independent alarm outputs.
8. How do I choose the right process indicator?
Start with the field input signal, engineering range, panel size, alarm requirement, transmitter excitation, retransmission and communication requirement. Then compare those requirements with the model datasheet.
