Unit description
8
3.6.2 RS 485 Interface
Connecting cable:
Thermostat
9-pin sub-D-socket
pin Data
1 Data A
5 SG (Signal Ground)
optional
6 Data B
☞
− Use screened connecting cables.
− Connect the screen to the plug case.
− The lines are electrically isolated from the remaining electronics.
− Unoccupied pins must not be connected!
The RS 485 bus absolutely needs a bus-termination in form of a terminating network, which ensures a
defined unattended time in the high resistance phases. The bus-terminal is defined as follows.
Generally this network is integrated on the plug in card of the computer (RS 485).
Protocol:
☞
− The interface operates with 1 stop bit, no parity bit and 8 data bits.
− Transfer rate either 2400, 4800, 9600 (factory setting) or 19200 baud as selected.
− The RS485 commands are always preceded by the device address. There is
provision for 127 addresses. The address must always have 3 digits. (A000_... to
A127_...).
− The command from the computer must be terminated with CR.
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