Central Processing Unit
5–14
1070 072 145-102 (01.07) GB
High-speed counters (ROD application)
The following peripheral conditions apply to operation with incremental ro-
tary transducers:
D The function is available for counter 1 only.
D The new mode is enabled by setting the MSB in word 20 of the OM2 orga-
nization module to HIGH. This leaves all remaining bits without signifi-
cance.
D The maximum counter frequency is 10 kHz or 10,000 lines per second.
D Counter 0 is restricted to limited simultaneous use, that is, without exter-
nal change of direction.
D System utilization at 10 kHz in Encoder mode is approx. 20 per cent.
D Encoder mode does not provide for setpoint value overrun.
D The new mode provides the PLC with a doubled-value interpretation, that
is, at 1000 lines per revolution, 2000 pulses are counted.
D Exceeding the permissible 10 kHz frequency will result in faulty counting
returns.
The delay of interrupt input 0 is modifiable. As a result, this high-speed input
can now also be used to recognize the LOW pulse of incremental rotary
transducers (ROD) having a pulse width of 100 ms. In such case the following
specifications apply:
Specifications High-speed counters as ROD
Counting frequency max. 10 kHz (excessive frequency re-
sults in faulty counting results)
Input delay
D LOW ³ HIGH
D HIGH ³ LOW
Typically 20 ms
Typically 20 ms
Pulse duration w 20 ms
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