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service pin LED
Reset
Service
Diagnostic
R X
UART1
TX
R X
UART2
TX
R X
UART3
TX
R X
UART4
TX
1 2
3
S3
Siemens Building Technologies
Cerberus Division
2
Product Description
2.1
CPU board
The CPU board is the main board. It must be present in any gateway GW-21, aside
from its configuration.
S4
NC
2
3
4
Flash EPROM
CPU
RTC
4
5
6
7
8
Fig. 1 The CPU board
On this board there are:
§ the CPU, the RAM and Flash EPROM
§ the Real Time Clock (RTC)
§ two UART chips, that manage the four GW-21 serial lines
§ the Neuron Chip, that lets the GW-21 to communicate with the LonWork network
§ four DIL switch blocks (S1 - S4), used to configure the GW-21 as described later
§ one reset push-button, used to reset the board
§ one service push-button, to send the service signal to the Neuron Chip
§ four sets of two LEDs. These LEDs show the status of UART RX/TX lines.
§ three LEDs used for diagnostic purposes.
For GW-21, the CD95800 board is configured as type 3 (check label on the RTC com-
ponent).
The three diagnostic LEDs marked LD1, LD2 and LD3 have the following meaning:
ON
(green
LD1
)
Firmware vitality failure or
out of memory jump
(red)
LD2
Download failed
(yellow)
LD3
-
Tab. 1
5
6
7
8
RAM
UART
UART
OFF
Firmware vitality failure or
out of memory jump
OK
-
8
Neuron
7
Chip
6
5
4
3
2
S1
1
8
7
6
S2
5
4
3
2
1
Blinking
Firmware vitality OK
Slow (1Hz): RAM test failed
Fast (4Hz): wrong configuration
or download in progress
-
3
E1481b
06.2000
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