SERVICE
33
MAGNET POWER SUPPLY SYSTEM 8500
4.2.2.
Real time clock:
IC13 with the crystal Y1 is the real time clock circuit. This clock circuit is used to catch the exact
time spot for the first arriving interlock after the last issued interlock reset.
This circuit is optional.
The clock can be set through SW commands. To maintain synchronized with the local time, it is
recommended to set the time at least every week. The clock is not designed for high accurate time
keeping.
A Lithium Cell of 3V type CR2450 ensures that the clock will continue running without the control
power. A red LED located beside the cell indicates if the battery needs to be replaced. (normally
after 5 years)
4.2.3.
Serial Communication:
The communication between the control board and the outside world can be performed through
serial links or a parallel CAMAC interface (See next paragraph). There are two serial communication
ports implemented for the communication.
A) Con. P14
RS422 to the M-PANEL (Chip IC4,IC5)
B) Con. P13
RS422/RS232 to the Remote control.
(Chip IC2, IC6 and IC7)
All serial communication lines are galvanically isolated from the
ì
P by means of opto couplers ISO1
to ISO6 and a separate isolated voltage supply. The lines are administered by the serial controllers
inside the CPU, controlling the baud rate, parity check and the data format (see page 5). The data
setting can be assigned either through the dip switches or through software. Please refer to chapter
3 for further information.
For isolation purposes the opto couplers PC400 with TTL logic output are used, and as for the TTL
to RS422 converter the SN75176 chip with three state output capability. The “three state” output
option is used when the system is connected in a multidrop mode. This permits up to 255 control
modules to be connected in parallel.
The RS232 line is driven by a MAX 232 or a LT1181 (IC2).
Switching between RS422, RS232 and RS485 (option) line operation is done by soldering one of the
0 Ohms resistor (or a strap) ST14 to ST16 for the remote line and ST9 to ST11 for the local lines See
schematic for more detail information which resistor selects which mode. This more complicated
way to select the working mode is chosen, to prevent accidentally change in working condition and
to minimize that more than one mode is chosen at one time. Ones it set, normally no change will be
needed later.
The data communication protocol is explained else where in the manual.
DANFYSIK A/S - DK 2630 TAASTRUP - DENMARK.
DOC NO P80303Sk