Siemens SIMATIC S7-1500/ET 200МР Manual page 75

Interrupts/diagnostic messages
5.2 Diagnostic alarms
Diagnostic alarm Error
code
Wire break at digital 505
input A, B or N
74
Meaning
Channel not connected
H
Resistance of encoder circuit too high
Interruption of the line between technology
module and encoder
Sensor used is sourcing output or sinking out-
put only
Remedy
Connect the channel
• Use a different encoder type or modify
the wiring, for example, use shorter
cables with larger cross-sections
• Check encoders
Check process wiring
Correct parameter assignment
Technology module TM Count 2x24V (6ES7550-1AA01-0AB0)
Equipment Manual, 12/2020, A5E31870371-AC