Siemens SIMATIC CM35, Руководство пользователя

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4-8
CM35 Counter Module
(4) J31069-D0416-U001-A5-7618
4.2.2 Parameterization via Direct I/O Accesses (Only SIMATIC S5)
Parameterization via direct accesses is only permitted in the ² period duration
measurement ² and ² timer ² operating modes.
The analog I/O address area contains 8 words. The data must be written with
word accesses.
The I/O address area is used for parameterization as shown below.
Table 4-4 Assignment of the address area for parameterization via direct I/O
accesses
Offset for the
Module Start Address
Description
+0 DO byte (digital output control)
may not be written during parameterization.
+2 Control word
+4 to +14 Parameterization data
The consistency (”C bit”) in the control word is used with direct--access para-
meterization to ensure consistency of the written values within one parameter
block.
The CM35 does not evaluate the transferred values of one parameter block as
long as the C bit is not set. These values do not become valid until the con-
trol word is written with C bit = 1.
The following sequence must be used to transfer the pafameter blocks.
1. Transfer the control word with C bit = 0.
2. Transfer all required data of the parameter block.
3. Transfer the control word with C bit = 1.
Transfer next parameter block.
Note
The channels may not be started or stopped by accesses to the control word
while parameter blocks are being transferred. The system must be in a de-
fined state before parameter blocks are transferred.
An example is shown below.
-- ² Timer ² operating mode
-- Transmission of the 1st parameter block from DB 20
-- The CM35 has the module start address 128.
Assignment of the
I/O address area
Use of the consis-
tency bit
Transmission of
parameter blocks
Data Communication with the CM35