Electrical connection

This page describes the connections of IOZER basic (IOZ-B-10) and the most important wiring requirements for installation in a control cabinet or suitable distribution board.

Connection by qualified personnel

Electrical connection may only be carried out by qualified personnel and only while the system is de-energized. Use a suitable SELV/PELV power supply and check the wiring before switching on the power.

No mains voltage

Direct connection to mains voltage, such as 230 V AC, is not permitted. This also applies to the relay outputs.

Power supply

IOZER basic is supplied with DC voltage through V+ and GND.

Connection	Value
Supply voltage	7–30 V DC
Power consumption	typ. < 5 W
Terminals	Duplicate terminals for loop-through wiring

Observe the polarity of the supply terminals. Before switching on the power, check the polarity, ensure there are no short circuits, and verify that the terminals are secure.

Digital inputs

The digital inputs are galvanically isolated and arranged in two groups of four inputs.

Connection group	Terminals	Notes
Inputs 1–4	`GND`, `1`, `2`, `3`, `4`	Shared ground terminal for each group
Inputs 5–8	`GND`, `5`, `6`, `7`, `8`	Shared ground terminal for each group

Signal levels:

Signal	Level
`0`	<= 2 V DC
`1`	>= 5 V DC
Undefined	> 2 V DC to < 5 V DC

The input voltage must not exceed 24 V DC. Each input has its own status LED.

Digital outputs

The digital outputs are normally open (NO) relay contacts arranged in two groups of four outputs.

Connection group	Terminals	Notes
Outputs 1–4	`COM`, `1`, `2`, `3`, `4`	Shared COM terminal for each group
Outputs 5–8	`COM`, `5`, `6`, `7`, `8`	Shared COM terminal for each group

Limits:

Parameter	Value
Output voltage	max. 30 V DC
Output current	max. 300 mA per channel
Switching capacity	max. 10 VA

Each output has its own status LED.

Communication interfaces

The following sections describe the wired communication interfaces of IOZER basic.

RS485

The RS485 interface can be used for Modbus RTU or IOZER link. IOZER link is intended for connecting IOZER expansion modules.

Terminal	Function	Note
`A`	RS485 data line A	Connect continuously to `A` on the remote devices
`B`	RS485 data line B	Connect continuously to `B` on the remote devices
`SHLD`	Shield connection	Connect the shield according to the system design

Operating modes

Operating mode	Use
Modbus RTU master	IOZER basic polls external Modbus RTU devices
Modbus RTU slave	IOZER basic provides data to an external Modbus master
IOZER link	Bus for IOZER expansion modules

The operating mode is selected in the device configuration. Only devices with compatible operating modes, baud rates, parity, stop bits, and addressing should be operated on the same RS485 bus.

Wiring

Wire RS485 as a line bus using a twisted pair for A and B. Avoid star configurations, rings, and long stubs. Polarity must remain consistent throughout the entire bus.

Use a shielded bus cable for longer distances or in environments with electrical interference. Do not connect the shield at multiple arbitrary points with different potentials. In typical control cabinet installations, connect it at one end or according to the grounding and shielding design of the system.

Termination

The 120-ohm bus termination can be enabled using a jumper. Enable termination only when IOZER basic is located at one end of the RS485 bus.

Position on the bus	Termination
End of the bus	Enable 120 ohms
Middle of the bus	Do not enable termination
Short laboratory or test wiring	Only if required

An RS485 bus is normally terminated at both physical ends. Intermediate devices are not terminated.

Commissioning

Wire A and B consistently on all devices.
Assign a unique bus address to every Modbus RTU device.
Configure matching baud rate, parity, and stop bits on all devices.
Enable termination only at the two ends of the bus.
Check shielding and reference potential according to the system design.
If communication fails, first check polarity, termination, bus parameters, and duplicate Modbus addresses.

1-Wire

The 1-Wire connection is used to integrate simple sensors, such as temperature sensors. IOZER basic provides +5V, DQ, and GND.

Terminal	Function	Note
`+5V`	Sensor supply	For 1-Wire devices with a 5 V supply
`DQ`	Data line	Also referred to as `DATA` or `1W`
`GND`	Reference potential	Route together with `DQ`

Property	Value
Maximum number of sensors	8
Supported sensor types	DS18B20, DS2438

Wiring

For new installations, three-wire wiring using +5V, DQ, and GND is recommended. This makes the installation more robust and easier to expand than a purely parasitic supply through the data line.

Shielded telecommunications or installation cables, such as J-Y(St)Y 2x2x0.8 or comparable KNX/twisted-pair cables, are suitable for typical installations. For maximum interference immunity, DQ and GND should use the same twisted pair. With cables similar to J-Y(St)Y, the shield or drain wire is normally not connected for 1-Wire and is not looped through at terminals.

Category cables may be electrically suitable but often have smaller conductor cross-sections. For longer cable runs or sensors with higher current consumption, larger conductor cross-sections and a topology without star branches are preferable.

Topology

1-Wire is more sensitive to unsuitable topologies than conventional fieldbuses. Keep the bus layout as simple as possible.

Topology	Rating	Note
Line	Recommended	Connect sensors one after another along one cable
Bus with short branches	Suitable	Keep branches as short as possible
Tree	Limited suitability	Only with manageable cable lengths and device counts
Star	Limited suitability	Only for small installations
Ring	Not permitted	Do not electrically connect the beginning and end

For mixed topologies, the restrictions of the least favorable section apply. If several sensor lines are required, it is usually better to plan them as cleanly separated lines instead of building one large meshed structure.

Parasitic power

Some 1-Wire sensors can be powered parasitically through DQ and GND. Use this mode only if the sensor, bus master, and firmware explicitly support it. For new installations, a supply using +5V, DQ, and GND is generally easier to maintain.

For simple DS18B20 sensor elements, parasitic operation may require connecting VDD to GND at the sensor. This bridge may only be installed at the sensor and according to its data sheet. The +5V output of IOZER basic must not be short-circuited.

Commissioning

Connect sensors one at a time where possible and detect each one using a 1-Wire scan.
Document sensor serial numbers together with their installation locations.
Create datapoints with unique names and units.
If readings are unstable, first check the topology, branch lengths, DQ/GND pair assignment, and power supply.
Avoid cables with strong interference, long parallel routing alongside load cables, or unclear terminal points.

Checks before switching on

Supply voltage and polarity checked
No connection to mains voltage
Terminals tightened securely
Suitable conductor cross-section and ferrules used
Input and output groups assigned correctly
RS485 shielding and termination checked against the bus layout
1-Wire topology checked; no ring, DQ and GND routed as a twisted pair

Additional limits are listed in the technical data.