Function Description - Siemens SIMATIC S5 Equipment Manual

5.1

Function Description

The arriving actual values (BCD or binary) are converted to ITL level by signal conditioning. These
values are transferred to the output memory and made available to the basic module.
This transfer is time delayed and only takes place at each change of the least significant data bit
In order to obtain short processing times, process the actual values and the setpoints in the same
format. See section 5.3.1.
Encoders with the following code types can be connected:
Dual (binary) maximum representation range O – 999991
Dual (binary) maximum representation range O – FFFFF
basic module.
2
Switch S1.1 and S1.2 closed (see section 5.3.1): the binary values are processed further with-
out conversion.
An adjustable time delay insures the acquisition of all bits which have changed. This delay time
must be adapted to the maximum encoder frequency.
The delay time should be less than or equal to half the interval between two pulses at maximum
encoder frequency.
By increasing C21 on the module, the delay can be increased.
State as delivered: 50 kHz = 10 psec delay (i.e., C21 = 3.3 nF).
Example: --t maximum encoder frequency
--t half interval = 300 psec
-t C21 = 30x 3.3 nF = 100 nF
AG
1989, Order No.: 6ES5 998-0KD21
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Matching Module 2 for Absolute Encoders
2
f = 1666 Hz
5 – 1