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Device handbook LINAX PQ3000-PQ5000
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5.11 Modbus interface RS485
Via the optional Modbus interface measurement data may be provided for a superior system. However,
the Modbus interface cannot be used for device parameterization.
1) One ground connection only.
This is possibly made within the
master (PC).
Rt:
Termination resistors: 120 Ω each
for long cables (> approx. 10 m)
Rs: Bus supply resistors,
390 Ω each
The signal wires (A, B) have to be twisted. GND (C/X) can be connected via a wire or via the cable screen.
In disturbed environments shielded cables must be used. Supply resistors (Rs) have to be present in bus
master (PC) interface. Stubs should be avoided when connecting the devices. A pure line network is ideal.
You may connect up to 32 Modbus devices to the bus. A proper operation requires that all devices
connected to the bus have equal communication settings (baud rate, transmission format) and unique
Modbus addresses.
The bus system is operated half duplex and may be extended to a maximum length of 1200 m without
repeater.
5.12 Uninterruptible power supply (UPS)
The
battery pack
for the uninterruptible power supply is supplied separately. Please note that compared to
the storage temperature range of the base unit the
storage temperature range
of the battery pack is
restricted.
Ensure that devices with uninterruptible power supply are used in an environment in accordance with the
specification
. Outside this operating temperature range, it is not ensured that the battery pack is
recharged.
Due to aging the capacity of the battery decreases. To ensure a successful operation of the device during
power interuptions the battery needs to be replaced every 3 up to 5 years.
Potential for Fire or Burning. Do do not disassemble, crush, heat or burn the
removed battery pack.
Replace battery pack with a
battery pack of the same type
only. Use of another
battery may present a risk of fire or explosion.