ABB Symphony Harmony Series - Page 163

4 - 8 WBPEEUI240751C0
Digital Input
across an input of one I/O module due to an I/O block fault
will result in a false, unchanging zero state input. An open in
an input channel circuit of the base will not allow either I/O
module to read the input.
An input state change error for a digital input will cause a fail-
over to the backup I/O module. This error occurs when one of
the digital inputs is changing state faster than the module can
handle. It is typically caused by a problem with the input
source. All digital channel LEDs will flash steadily and at the
same rate to indicate this type of error.
Figure 4-5. AIN-220 Block - Current Mode (IFP or LFP Powered)
T03241A
REF1
REF1
REF16
REF16
1
1
16
16
CH 1
CH 1
CH 16
CH 16
•
•
•
•
•
•
•
•
•
•
•
•
AIN-220 MODULE
AIN-220 MODULE
REDUNDANCY LINK
REDUNDANCY LINK
AMP
AMP
AMP
AMP
A/D
A/D
A/D
A/D
OPTO-
COUPLER
OPTO-
COUPLER
OPTO-
COUPLER
OPTO-
COUPLER
A
A
A
B
B
B
HNET
CPU
AND
HNET
IN T E R FACE
CPU
AND
HNET
IN T E R FACE
+
+
+
+
REDUNDANT
AIN-220 BASE
–
–
–
–
+
+24 V
150
τ
250 τ
IF P /L FP
–
IF C /L FC
4-20 mA
LOOP