Siemens Industry Online Support
Siemens AG
Entry type: Product note Entry ID: 4140084, Entry date: 08/27/1996

Notes on the Connection of 485-7LA11 Modules

  • Entry
  • Associated product(s)


Concerns the product with Order No.:                                        


6ES5 485-7LA11   Digital I/O module for S5-115U                             




The I/Os of this module require an external load supply voltage.            

For the inputs and output byte "x" this supply is connected to              

pin 36 (L1+) and for output byte "x+1" to pin 38 (L2+). If the              

L1+ supply fails (pin 36) the inputs are read as being "0" and              

the LEDs are switched off.                                                  


Please add the following notes to the Product Leaflet, page 9:              


"The LEDs for the inputs and the outputs are controlled from the            

 5V-circuits of the module. This results in the following                   



 - A "1" input signal is only detected and displayed via LED if             

   the PLC power supply and the load voltage L1+ (on pin 36) are            

   switched on.                                                             


 - Output LEDs can signal a "1" status, even though the 24V load            

   supply voltage is missing or the output is short-circuited."             




We wish to point out that the module is non-isolated and that the           

installation guidelines of the S5-115U Manual, particularly                 

those concerning the reference voltage, must be adhered to. For             

instance, if the reference voltage of the external process                  

signals (Mext) is not connected to the internal reference voltage           

(Mint or PE), wrong input signal statuses will possibly be read.            




Security information
In order to protect technical infrastructures, systems, machines and networks against cyber threats, it is necessary to implement – and continuously maintain – a holistic, state-of-the-art IT security concept. Siemens’ products and solutions constitute one element of such a concept. For more information about cyber security, please visit