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Status after switching on, Individual start of an adc channel – Siemens Simatic S7-400 User Manual

Page 545

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Interface Submodules

13-49

S7-400, M7-400 Programmable Controllers Module Specifications
A5E00069467-07

Table 13-42

Meaning of the Control Bits in the Analog Input Function (IF 961-AIO)

Offset

Address

D15

Writing

D0

Remark

08

H

A
C

I

N

T

0

0

0

0

0

0

0

0

0

0

0

ta

ta

ta

Control register 1

0A

H

0

0

0

0

0

0

0

0

0

0

0

0

0

ADC

channel no.

Control register 2

0C

H

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

S
C

Status register ADC

0E

H

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

Acknowledge
interrupt
x = any

ta = 000
ta = 001
ta = 010
ta = 011
ta = 100

AC = 1

INT = 1

ADC channel no.
ADC = 001
ADC = 010
ADC = 011
ADC = 100

SC = 1

5.7 ms cycle time of the automatic conversion function
2.8 ms
1.3 ms
600

µ

s

185

µ

s

Automatic conversion of all ADC channels active

Generation of an interrupt after end of cycle

Number of the selected ADC channel:
channel 0
channel 1
channel 2
channel 3

Start of analog-digital conversion, (SC = Start of conversion in the case of individual
encoding)

Status After Switching On

Control register 1:

AC = 0, INT = 0, ta = 0

5.7 ms

Control register 2:

ADC = 001

ADC channel no. = 0

Status register ADC:

SC = 0

Individual Start of an ADC Channel

Below are listed the steps required for individual encoding in the case of an ADC
channel:

1. Select the ADC input channel by writing the channel number into control register

2 (offset address “0A

H

”).

2. Start the ADC conversion by setting the SC bit in the status register ADC to “1”

(offset address “0C

H

”).

3. Read bit “EOC” in the status register ADC at offset address (0C

H

) and wait until

EOC = 1.

4. Read the analog value at the relevant address (offset addresses “00

H

” to “06

H

”).

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