S2000M MAINTENANCE
GUIDE
21
2)
There is some switching delay required when the control is taken over for false switching
protection, device detection period and for initiation. The more system is greater the more
switching delay is needed.
The switching criterium is the absence of computer polling during given time.
There are two ways of switching the control from PC to the console: 1) by means of self-
acting mechanically RS-485 lines switching with the help of “S2000M-SP1” relay units and 2)
using the
special
console operating mode, that is
interface converter mode
with automatic transit
to redundant mode.
The first way supposes the console to be physically disconnected and is described by the
“S2000M-SP1” maintenance guide. One shoulde use the “S2000M-SP1” device version 1.20 or
above.
The second way supposes the console to be directly connected to the computer via RS-
232 interface, with the the devices being connected to the console through RS-485 interface.
Being operative ’ARM Orion’ polls all the system devices but the console execute the
RS-232/RS-485 convertor function without galvanic separation. The console doesn’t control
devices, doesn’t show their states and is unresponsive to key pressions. LCD displays the “S2000
/ PC” string and the “READY” indicator blinks to show the data transmission.
If the computer doesn’t poll the devices during a given time period then the console
automatically switches to the active mode. The switching delay is nesessary against false
switchings due to the polling intervals.
To configure this switching way set the RS-232 operating mode to the “S2000 / PC”
value and give the switching delay as described in section 2.2.4.8. It is recommended to set the
switching delay at least 60 seconds.
Two above switching ways are just alike in terms of capabilities. Their benefits in
comparison with each other are as follows:
switching by means of ‘S2000-SP1’
switching from “S2000 / PC” mode
1)
The galvanic isolation is like to be at less
cost
2)
Old messages stored by the console in
backup mode are available
3)
It is possible to connect printer to the
console
1)
in case of sophisticated system it is more
suitable for usage of several consoles for
redundancy
2)
when switching the controlling from the
console to the PC the console will not give
messages about device disconnections
The
second reserving mode
called as
‘S2000 & PC’
is that the console is to be directly
connected to the computer via RS-232 interface, with the the devices being connected to the
console through RS-485 interface. The console monitors all the devices and gets their states,
with the computer polling the concole (or consoles) and getting the device operative information.
Both the console and the computer can control the relay outputs and indication units. If the
computer fails the console will retain to execute the controlling functions. This reserving mode
has the following advantages:
1)
The devices are available for controlling by the console when the PC operates normally. If
the PC supplied with ‘ARM Orion’ software failes the event messages are storied in the
console buffer and can be readed after the computer restoring.
2)
As a result of absence of switching between the console and PC there is no switching delay.
3)
Delegating the console some controlling functions unloads the PC.
