Ultrasonic sensor

01

Check range, blind zone and target

Dianyingpu (DYP) publishes its A02 waterproof ultrasonic module with these figures [2].

The approximate 60° figure and the plotted detection curves belong to specified targets. A tube and a broad carton produce different curves; this is not a constant cone that proves every object inside it will be detected. [2] [4]

02

Two acoustic faces, a processing board and an output selected at ordering

DYP describes a bistatic probe and shows housed and uncased assemblies. This functional reference explains the component roles; it is not a teardown or a replaceable-part manufacturing BOM. [2]

For maintenance or spares, ask for the actual assembly revision and service policy. The uncased board and housed sensor are distinct ordering choices, not permission to open a sealed unit.

03

Calculate accuracy at your distance

The A02 accuracy is ±(1 + S × 0.3%) cm for UART, switch and RS485 versions and ±(1 + S × 0.5%) cm for PWM, where S is distance in cm [2].

CNFX arithmetic from the manufacturer formulas. The datasheet condition is 25 °C, 65% RH and a 50 × 60 cm flat carton, approximately normal to the probe. Its table marks PWM temperature compensation N/A, whereas the PWM interface text mentions internal compensation. Obtain a corrected description and qualify the ordered version across the application temperatures. [2] [3]

04

Pick the output and read it correctly

Choose the output before ordering. The A02 pin functions correspond to that version and do not coexist with the other output modes; the manuals do not establish a field-selectable all-interface unit. [3] [2]

UART format

TTL, 9,600 bps, 8 data bits, 1 stop bit, no parity; frame = 0xFF, Data_H, Data_L, SUM [3]

Worked frame

0xFF 0x07 0xA1 0xA7: distance = 0x07 × 256 + 0xA1 = 1,953 mm; SUM = (0xFF + 0x07 + 0xA1) & 0xFF = 0xA7 [3]

Auto mode filtering

RX high or open: processed, more stable value with 100–500 ms response; RX low: real-time value with 100 ms response [3]

Controlled mode

Measures after a falling edge or any serial byte on RX; trigger period must exceed 70 ms [3]

PWM requires a valid-echo decision

The manual gives a falling-edge trigger, period over 70 ms and a high pulse whose duration represents travel time. It also outputs about 35 ms when no object is detected. Obtain and test the valid/no-echo rules; do not turn that fallback pulse into a normal distance reading. The compensation wording conflicts with the datasheet. [3] [2]

Switch output is logic, not a power switch

The manual gives a factory 1.5 m threshold, a 100 ms measurement cycle and three consecutive below-threshold or five above-threshold results before changing state. TX is explicitly high/low logic without driving capability. Confirm the interface circuit; do not connect it as a 24 V PLC power output or treat the threshold as a safety function. [3]

RS485 uses its own data map

This A02 manual specifies Modbus RTU, 9,600 bps, 8N1 and CRC-16/MODBUS. Processed distance at 0x0100 is in millimetres with 500 ms response; real-time 0x0101 is about 100 ms. The address register is marked read-only although a later example writes it. Obtain the corrected map before changing addresses; the UART four-byte frame is not the RS485 frame. [3]

05

Power it and mount it

Average current hides the transmit pulses that a supply must handle [2].

Average current

≤8 mA for non-RS485 versions; ≤15 mA for RS485 in the cited 5 V / 100 ms test, at 25 °C and 65% RH. These are the datasheet’s typical-test figures, not the peak load. [2]

Peak current

≤ 40 mA (≤ 75 mA RS485) [2]; size regulators and battery wiring for the peak

Supply quality

Input ripple max. 50 mV, noise max. 100 mV peak [2]

ESD evidence

The datasheet lists ±4 kV / ±8 kV and refers to IEC 61000-4-2, but the wording does not clearly allocate both levels to the complete installation and discharge methods. Request the actual test report; this page does not claim independently certified system immunity. [2]

Two or more sensors

Pepperl+Fuchs spacing figures are guidelines for aligned sensors and defined targets; other orientations require experimental spacing. Synchronisation/multiplexing is an option on capable models, not an established A02 feature. Test cross-talk with all installed sensors running. [5] [3]

Chemicals

Pepperl+Fuchs describes limited resistance of its standard transducer materials and specialist PTFE/stainless constructions. Those materials are not the A02’s verified internal BOM. DYP describes the housed A02 as PVC; IP67 does not establish resistance to a cleaning chemical, immersion service or vessel pressure. Obtain media/cleaning compatibility for the actual assembly. [5] [1]

06

Write the target, timing and enclosure conditions beside the electrical fields

Use these fields to define the selected module and its installation. An unknown value remains a supplier question; no generic ultrasonic-sensor range or material is substituted.

07

Qualify the echo and keep the no-target result out of the control decision

Record readings on the real object before treating the module as a machine input. DYP calls for structural-tolerance and system EMC evaluation; Pepperl+Fuchs explains target and cross-talk effects. [2] [4] [5]

Installed target trial

Check the nearest and farthest required positions, surface angle and surrounding reflectors. Compare output error against a known distance, then repeat over the expected ambient conditions. This is an acceptance proposal, not a CNFX test result.

Signal validation

For UART verify header, length and low-byte checksum before accepting distance; for RS485 use its CRC/register format. Define missing/stale/no-echo handling with the supplier. The manual does not establish a universal diagnostic output for every failure. [3]

Troubleshooting and care

When readings shift, compare target alignment, obstructions, output/filter mode, supply quality and neighbouring sensors before replacing the unit. Follow supplier-approved cleaning for the exposed materials; no solvent, universal cleaning interval or sealed-case teardown is prescribed. [2] [5]

Replacement record

Keep part number, output version, hardware/firmware, cable/mount drawing and validated timing. Recheck the actual target and invalid-reading behaviour after replacement; similar four-pin connectors do not prove equivalent supply or signal roles. [2] [3]

08

Copy the echo, interface and acceptance requirements

Paste it into your enquiry below or into an email to a maker, then replace every bracket.

Product: ultrasonic distance module, quantity [ ]; housed/uncased [ ], exact output part number/revision [ ]
Target: material/size/shape [ ], surface angle [ ], nearby reflectors [ ]
Distance: required near/far [mm], permitted error at each point [mm], required smallest detected change [ ]
Ambient: temperature/humidity [ ], condensation [ ], pressure [ ], cleaning chemicals/media [ ]
Interface: UART auto/controlled, PWM, logic switch or RS485 [ ]; controller voltage/circuit [ ]
Timing: update/response [ms], filter/threshold persistence [ ], invalid/no-echo/stale-reading rules [ ]
Supply: voltage/variation [ ], peak-current capacity [ ], ripple/noise [ ]
Mounting: drawing/revision [ ], bracket and cable [ ], adjacent sensors [ ], cross-talk test [ ]
Evidence: corrected PWM compensation, supply/storage conflicts, protocol/address permissions and IP test scope [ ]
Acceptance: real-target measurements across required distances/angles/temperatures [ ], controller error handling [ ]
Delivery: destination/date [ ], spare/replacement configuration [ ]

See manufacturer records Send an enquiry through CNFX