6ES7135-6HD00-0BA1 ET200 SP Analog output module resolution

Hello,

I found one thing unclear in 6ES7135-6HD00-0BA1 manual. There is following information:

Let's keep in mind that:

Bit values

14th bit = 8192

15th bit = 16 384

16th bit = 32 768

27648 = 0110'1100 0000'0000

Few pages later there is a page with following information

Manual

Table B-9 Current output ranges 4 to 20 mA

100 %  DEC 27648 = 20 mA

0.003617 % DEC 1 = 4 mA + 578.7 nA

0 % DEC 0 = 4 mA

Table B-9 says clearly that 100% is 27648 so we still need 15 bits to express this value.

If so, then what's the meaning of 14 bits resolution? 

16 mA range / 578.7 nA increment value = 27 648 increments - so it seems that hardware is capable of outputing 15 bit increments.

Does anybody know the answer?

Hi Konop857,

Siemens uses left-aligned values for analog devices. This makes the conversion independent of the actual resolution of the module. For details see the function manual 'SIMATIC S7-1500, ET 200MP, ET 200SP, ET 200AL, ET 200pro, ET 200eco PN Analog value processing'.

Kind regards
Stefan

Stefan Arcularius

Hi Konop857,

Siemens uses left-aligned values for analog devices. This makes the conversion independent of the actual resolution of the module. For details see the function manual 'SIMATIC S7-1500, ET 200MP, ET 200SP, ET 200AL, ET 200pro, ET 200eco PN Analog value processing'.

Kind regards
Stefan

 Hello,

thank you for answer.

Does it mean that 14 bit value skips 2^0 and 2^1 values? Therefore minimal INT increment would be 4 which equals 4*578.7 nA.

Hi Konop857,

Konop857

Hello,

thank you for answer.

Does it mean that 14 bit value skips 2^0 and 2^1 values? Therefore minimal INT increment would be 4 which equals 4*578.7 nA.

Yes, if only 14 of the 16 bits are used, the two least significant bits are skipped.

Kind regards
Stefan