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G1  Introduction to AC500  1-56  AC500 / Issued: 07.2006 
 
LEDs on S500-FBP modules 
All S500 modules have LEDs for the display of operating statuses and error messages. They indicate: 
LED  Meaning  Color  LED = ON  LED = OFF  LED flashes 
digital input  yellow  input = ON  input = OFF  -- Input 
analog input  yellow  brightness depends on the value of the 
analog signal 
-- 
digital output  yellow  output = ON  output = OFF  -- Output 
analog output  yellow  brightness depends on the value of the 
analog signal 
-- 
UP process 
voltage 24 V 
DC via 
terminal 
green  voltage is present  voltage is missing  -- 
PWR  24 V DC via 
FBP 
green  voltage is present  voltage is missing  -- 
S-ERR  Sum Error  red  serious error, data 
exchange is 
stopped, depends 
on the behaviour of 
the master 
no error  error (e.g. error 
on one 
channel, data 
exchange is not 
stopped 
FBP FBP 
communication 
green communication 
between FBP and 
FBP Interface 
Module is running 
communication 
between FBP and 
FBP Interface 
Module is broken 
during 
initialization 
I/O-Bus I/O-Bus 
communication 
green communication 
between FBP 
Interface Module 
and the I/O 
modules is running 
no communication 
between FBP 
Interface Module 
and the I/O 
modules 
error on one I/O 
expansion 
module (e.g. 
one output 
short-circuited) 
CH-ERR1 red 
CH-ERR2 red 
CH-ERR3 red 
CH-ERR4 
Channel Error, 
error 
messages in 
groups (digital 
or analog 
inputs and 
outputs 
combined into 
the groups 1, 
2, 3, 4) 
red 
serious error within 
the corresponding 
group 
no error  error on one 
channel of the 
corresponding 
group (e.g. one 
output short-
circuited) 
CH-ERR 
*) 
Module Error  red  error within the I/O 
module 
-- -- 
*) All of the LEDs CH-ERR1 to CH-ERR4 (as far as they exist) light up together 
For the meaning of the different LEDs and their behaviour when the system is running, please refer to 
the S500 System Data of the S500 User’s manual for further information.