sauter EQJW145, Operating Manual

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EQJW145: Heating controller
Communication functions
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© Fr. Sauter AG
6 Communication functions
The EQJW 145 has a communication interface which can be used for the
device bus, or alternatively for Modbus communication – also via modem.
Fault messages can still be sent by modem to a mobile phone as SMS
messages.
6.1 Bus wiring
The rules for RS-485 bus systems must be followed when setting up
communication networks. The following points must be noted in particular:
Maximum length of one bus segment: 1,200 m
Maximum number of devices: 32
A final resistance (120 Ohm) must be provided at the end of the line
Use twisted pair screened cable
Stub cables in excess of 3 m in length are not allowed
Screens must be applied flat on both sides, according to the rules of
engineering, and must be connected to earth with low resistance
External lightning and surge voltage precautions must be provided if
cables are laid beyond the boundaries of the building
It is not necessary to keep to a specific polarity (cores A/B) with the EQJW
145.
6.2 Device bus
The device bus makes it possible to interconnect as many as 32 devices with
little outlay. It is primarily used to transmit measured temperature values
(outdoor temperature and room temperature) and commands (mode
changeover). Connecting the devices only requires two wires which are
attached to the terminals regardless of polarity – to terminals 18 and 19 on
the EQJW 145.
6.2.1 Assigning addresses
Every device in the grouping must be assigned a unique bus address.
Address '1' must occur once in each grouping. To enable the device bus,
parameter CP02 must be set to '1'. Then the address has to be set
(parameter CP04).
If a device in an installation that is in operation is exchanged and the
addresses used are not known, the 'Automatic address assignment' function
can be used (CP04 =
A u t o
). This causes the controller to search the bus
for an unused address which it sets as parameter CP04.
Please note these points about automatic address assignment:
All the other devices in the installation must be switched on.
Only one device must execute the function at a time.