Analog signal types describe how a measured or commanded value is represented electrically. A 4-20 mA current signal and a 0-10 V voltage signal require the corresponding documented receiving interface. Neither label, by itself, identifies the physical quantity or the meaning of the displayed number.
For an aluminum-cutting machine proposal, ask what each signal does and where it goes. These three checks of analog signal types cover the electrical format, the value mapping and the documented response outside the normal measurement range.
Read the signal in three layers
- Format: what output is connected to what receiving input?
- Meaning: what physical range and direction does it represent?
- Response: what does the system report when the normal signal is unavailable?
1. Match the analog signal types at the interface
Write the sender and receiver as two separate entries. Identify the exact sensor or transmitter output, then the receiving device and channel. A quotation that lists “analog input” without a supported format leaves the interface unresolved.
Phoenix Contact’s analog-signal manual describes 4-20 mA as a standard current range and 0-10 V as a standard voltage range. It distinguishes current sources from passive current outputs, and explains that permitted loading and supply conditions belong to the device documentation. A shared range label does not settle those conditions.
Ask for the approved interface drawing and the relevant datasheets. Keep the complete part numbers, configured range and channel identity visible. A connector that looks familiar does not establish the format of the electrical input behind it.
Also separate signal range from power supply. A sensor’s stated supply voltage and its stated output range describe different entries in the specification. Do not copy one into the other field when summarizing the offer.
If the proposed formats differ, ask the controls supplier to explain the interface solution. Phoenix Contact’s manual describes converters between standard current and voltage signals. The proposal should identify any required device and its approved role rather than assume that two different formats connect directly.
This is a document review for a purchase, not a terminal-by-terminal wiring procedure. Have the responsible controls team approve the actual device combination and implementation.
2. Connect the electrical range to the displayed value
The electrical endpoints need a physical meaning. Identify the measured quantity, its unit, the configured minimum and maximum, and the intended direction of the mapping. The same signal range can represent different quantities in different applications.
Banner’s S18U analog-output datasheet provides a specific sensor example. It lists current and voltage output versions and describes a programmed sensing window with either a positive or negative output slope. Those features belong to that product; they illustrate why an output range alone does not define the measurement mapping.
Ask the supplier to show the configured endpoints in the delivered documentation. If increasing the physical value decreases the output, the receiving system must interpret that relationship as approved. Avoid assuming that every signal rises with the quantity being measured.
An invented linear mapping: halfway through the range
For this teaching example only, assume an ideal positive linear mapping from 0 to 100 arbitrary units. The current version represents those endpoints with 4 and 20 mA; the voltage version uses 0 and 10 V. This is not a sensor recommendation or a machine measurement.
At 50 units, the fraction of the physical range is 50 ÷ 100 = 0.5. The assumed current is 4 + 0.5 × (20 − 4) = 12 mA. The assumed voltage is 0 + 0.5 × (10 − 0) = 5 V.
| Assumed physical value | Current | Voltage |
|---|---|---|
| 0 units | 4 mA | 0 V |
| 50 units | 12 mA | 5 V |
| 100 units | 20 mA | 10 V |
The current midpoint is 12 mA because its range begins at 4 mA. Treating the same 12 mA as a fraction of 0-20 mA would give 12 ÷ 20 = 0.6, or 60 units in that different assumed mapping. The arithmetic shows why the receiving range must match the intended one.
It does not establish actual accuracy, resolution or response time. Ask for those requirements separately where the application needs them. Keep the displayed unit and the approved scaling record alongside the electrical format.
3. Ask what the system reports outside the normal range
Phoenix Contact explains that 4 mA represents the minimum of that current range. With a zero-based range, zero alone cannot distinguish a valid minimum from an interrupted measurement path.
The actual response still needs product and system documentation. Banner’s cited S18U datasheet, for example, states specific outputs on signal loss. That product example does not establish the thresholds or responses of another sensor or controller.
Ask which condition the device detects, what output it produces and how the receiving system handles it. Retain the documented status or alarm meaning in the proposal. Do not classify every value outside the assumed range as the same fault.
For a sample review, agree which conditions and observations the authorized team will record. A screen photograph can show a displayed value; it cannot prove the entire signal path, range configuration or response to a missing measurement.
Keep analog signal types separate from switching-output terminology. Our PNP versus NPN sensor guide addresses switching arrangements. Those labels do not substitute for identifying an analog current or voltage range.
A short handover record for analog signal types
Request the sender reference, receiver and channel, electrical range, physical unit, configured endpoints, mapping direction and documented abnormal-condition response. Identify who provides and verifies the delivered configuration.
Keep revisions linked to the actual offered configuration. If a sensor version or input module changes, have the responsible team review the interface and mapping again. An unchanged screen label does not establish that the replacement is equivalent.
Buyer questions about analog signal types
Does 4 mA mean zero current?
No. In the example it is the electrical value assigned to the physical minimum. The meaning depends on the approved mapping.
Does a 0-10 V output identify the measured unit?
No. Request the physical quantity, configured range and receiving-system interpretation.
Does an analog signal establish a machine’s cutting accuracy?
No. Signal format and cutting performance are separate requirements. Review the specified finished parts and the agreed measurement evidence.
Make integration requirements visible in the machine inquiry
Send JiurunCut your cutting job and required integration scope. Include the section drawing, part quantities and any interface documentation requirement. Ask for the actual offered controls configuration and its handover records.