Burkert Type 8318 (Model 574629) pressure transmitter measures and monitors relative pressure in liquids and gases. The effect of the pressure on the sensor element generates a signal which is amplified, digitised, and processed. Instead of an analogue output, this device offers a digital IO-Link interface (specification version 1.1), allowing bidirectional data transfer with any IO-Link master. Data access occurs through the available standardised IO Device Description (IODD).

The bidirectional communication is used to read process data, parameters, diagnostic information, and status messages, as well as to set parameters. The two green LEDs are permanently lit as soon as power is supplied to the device. Once an IO-Link connection has been established, the LEDs flash. The switching behaviour and the switching thresholds of the digital outputs (maximum of 2, "PNP" or "NPN") can be individually configured.

Key Features

• Metallic thin film strain gauges measurement principle
• Process connection: G 3/4 with hygienic flush diaphragm (ISO 228-1)
• Measuring range for relative pressure: -0.4...+0.4 bar
• Available switching functions: PNP or NPN
• Access to measured value, device status, and settings through IO-Link interface, enabling very easy sensor replacement

Display and Connection Elements

1. Status LEDs
2. Pressure connection with membrane for recording pressure levels
3. M12 connection
4. Protective cap for storage and transport

General Technical Data

Material and Performance

Property	Description
Housing	Stainless steel 1.4301 (304)
Process connection	Stainless steel 1.4404 (316L)
Measuring element	Membrane in stainless steel 1.4435 (316L), Welding ring in stainless steel 1.4404 (316L)
Measurement technology	Metallic thin film strain gauge
Measuring range	-0.4...+0.4 bar
Measurement deviation	At 20 °C: 0.7% of measuring span At -20 °C...+80 °C: 2.0% of measuring span
Linearity	0.3% of measuring span
Overload limit	1 bar
Burst pressure	1.5 bar
Response time	Digital switching output: ≤7 ms IO-Link: ≤9 ms

Electrical and Output Data

Property	Description
Operating voltage	In IO-Link operation: 18...32 V DC, filtered and regulated In switch operation: 9.6...32 V DC, filtered and regulated
Current consumption	In idle operation: ≤ 10 mA In IO-Link operation: ≤ 12 mA In switch operation: ≤ 250 mA (with two digital outputs)
Number of outputs	1 digital output in IO-Link operation 2 digital outputs for switch operation (SIO-mode)
Switching function	Hysteresis function (configurable) or window function (fixed setting, symmetrical, ± 0.25% of the measuring range) NC or NO contact Digital output PNP or NPN Switch-on/switch-off delay (0...100 s)
Switching current	≤ 100 mA per output
Electrical connection	M12 × 1 male connector, 4 pins, A-coded, non rotating (IO-Link port class A)

Medium and Environment

Property	Description
Fluid	Liquid and gaseous medium
Fluid temperature	-40...+125 °C (-40...+257 °F)
Ambient temperature	Operation and storage: -40...+85 °C (-40...+185 °F)
Degree of protection	IP65 according to DIN EN 60529, with female connector screwed on

Dimensions

With G 3/4 front-flush process connection according to ISO 228-1

Note: Dimensions in mm. The total height is increased by the height of the used female connector and cable.

Electrical Connection

M12 × 1 round plug (A-coded, non rotating) Terminal Assignment

Connection	Pin	Assignment
Switch operation
Voltage supply DC 9.6 to 32 V	1 BN (brown) 3 BU (blue)	L+ L-
Switching output 1	4 BK (black)	C/Q = OUT1
Switching output 2	2 WH (white)	I/Q = OUT2
IO-Link operation
Voltage supply DC 18 to 32 V	1 BN (brown) 3 BU (blue)	L+ L-
IO-Link	4 BK (black)	C/Q = IO-Link
Switching output 2	2 WH (white)	I/Q = OUT2

WARNING

The auxiliary energy of the pressure sensor must meet SELV requirements; optionally, an energy-limited current circuit according to DIN EN 61010-1 and UL 61010-1 can be used. The pressure sensor must be connected to the plant's potential equalization system via the process connection.

Functions

Hysteresis Function

The hysteresis function switches the output as soon as the switching point "SP" is reached. When the release point "rSP" is reached, the output switches again. The hysteresis function distinguishes between N/C and N/O contacts.

Switching requirement: Switching point "SP" ≥ Release point "rSP"

Window Function

Under the window function, the window range is defined using the parameters window low "FL" (lower value) and window high "FH" (upper value). The output switches when the current measured value (x) is between the two limits.

Requirement: Window high "FH" >= Window low "FL"

The window high "FH" and window low "FL" switching points have a fixed symmetrical hysteresis of ± 0.25 % of the measuring range.

Switch-on Delay / Switch-off Delay

The switch-on delay "VSP" and switch-off delay "VrSP" prevent switching of the output being triggered by peaks or drops in the measured values. If the necessary measured value is no longer measured once the delay time has passed, the output is not switched.

Fine Adjustment

You can use customer-specific fine adjustment to correct the measured values of the sensor. In contrast to offsetting, which is used to specify a constant correction value for the entire characteristic line, fine adjustment can also be used to change the gradient of the characteristic line.

TIP

The actual start value and actual end value can also be selected with the teach function. The fine adjustment data are not stored in the parameter manager.

Parameter Overview

Process Data

The data is transferred in a cycle via the IO-Link interface to the IO-Link master (PDI = Process Data Input). The entire process data can be extracted via index 40 and subindex 0.

Designation	Data type	Default	Description
Pressure process value	TFLOAT or TINT32	0	The "Data format" configuration parameter can be used to switch between data types.
Pressure process value unit	TUINT8	bar	0 = bar, 1 = mbar, 5 = psi, etc.
Pressure process value status	TUINT8 (bit field)	0	Bit 0 = Process value invalid Bit 1 = Error in configuration data Bit 2 = Error in calibration data
Switching output	TUINT8 (bit field)	0	Bit 0 = Switching output 1 Bit 1 = Switching output 2 (0 = Not switched, 1 = Switched)

Configuration Data

The configuration is stored in the parameter manager and is transferred via the IO-Link interface in an acyclic process.

Designation	Index	Data type	Default	Access
Data format	64	TENUM (1 byte)	Floating point	RW
Pressure process value unit	120	TENUM (1 byte)	bar	RW
Pressure process value offset	121	TFLOAT	0	RW
Pressure filter time constant	122	TFLOAT	0	RW
Switching behavior (Out 1/2)	200 / 201	TENUM	Inactive	RW
Switching point/Window high	200 / 201	TFLOAT	0	RW
Release point/Window low	200 / 201	TFLOAT	0	RW
Switch-on delay	200 / 201	TFLOAT	0	RW
Switch-off delay	200 / 201	TFLOAT	0	RW
Output mode	200 / 201	TENUM (1 byte)	P-switching	RW

Fault Signaling

IO-Link offers a range of fault signaling options (device status, event codes, PDValid-Flag). Malfunctions can also be signaled within the process data via the process value itself or the status of the process value.

Description	Process value status in PDI	Device status	Event code	Event error type
Process value invalid	Bit0 (Process data invalid)	4 (failure)	0x1000	Error
Overrange	Bit0 (Process data invalid)	4 (failure)	0x8C20	Error
Underrange	Bit0 (Process data invalid)	4 (failure)	0x8C20	Error
Error in configuration data	Bit1 (Parameter error)	4 (failure)	0x6320	Error
Device is defective	Bit2 (Device is defective)	4 (failure)	0x5000	Error
Undervoltage	-	2 (Outside spec)	0x5111	Warning
Temperature error, overload	-	4 (failure)	0x4000	Error