System of servicing device and field device and method for communication with a field device

1. A system comprising:

a servicing device;

a field device having at least one sensor unit for determining and/or monitoring at least one process variable; and

at least one electronics unit, which has an evaluation unit, wherein:

said evaluation unit receives measurement signals from said sensor unit and evaluates such with reference to the process variable, and at least one switch element actuatable contactlessly from outside of said field device; and

said servicing device is embodied to modulate the switch state of said switch element for transmission of field device specific parameter data or diagnostic data to said electronics unit, wherein:

said switch element is actuatable from outside of said field device via a magnetic field; and

said servicing device produces a modulatable magnetic field.

2. The system as claimed in claim 1 , wherein:

said field device includes at least one optical display element; and

said electronics unit transmits data to said servicing device via said optical display element.

3. A field device for application in a system as claimed in claim 1 , wherein:

said field device comprises at least one sensor element for determining and/or monitoring at least one process variable;

at least one electronics unit;

at least one switch element actuatable contactlessly from outside of said field device; and

said electronics unit is embodied to receive field device specific parameter data or diagnostic data via said switch element.

4. A servicing device for application in a system as claimed in claim 1 , wherein:

said servicing device comprises at least one field producing unit for producing a modulatable magnetic field;

said field producing unit is embodied in such a manner that the magnetic field produced by said field producing unit modulates the switch state of said switch element of said field device.

5. The servicing device as claimed in claim 4 , wherein:

said servicing device includes an optical sensor system, which registers optical signals coming from said field device.

6. The servicing device as claimed in claim 4 , wherein:

said servicing device has a second electronics unit and means for input of field device specific data or is connectable with a second electronics unit and means for input of field device specific data;

said second electronics unit contains a protocol for transmission of field device specific data to said field device; and

said second electronics unit controls said field producing unit in such a manner that said field producing unit produces the magnetic field corresponding to the protocol and to the specific parameter data or diagnostic data to be transmitted.

7. A method for communication between a servicing device and a field device having at least one sensor unit, at least one electronics unit and at least one switch element actuatable contactlessly from outside of the field device, wherein:

for transmission of field device specific data from the servicing device to the electronics unit the switch state of the switch element is modulated.

8. The method as claimed in claim 7 , wherein:

the switch state of said switch element is modulated according to a transmission protocol.

9. The method as claimed in claim 7 , wherein:

parameter data and/or diagnostic data are transmitted by means of said switch element.