Specifications

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C-11
C Buep 19e-Expander driver
Data transmission PCS-PLC Data transfer between the PCS and the PLC is effected in data packets.
Each data packet is assigned a checksum (CRC). The package content
is checked for possible errors by the PLC operating system and the PCS.
Each packet consists of a minimum of one sub-packet which performs a
clearly defined task. The tasks to be integrated in a packet are determined
by the PCS based on numerous single criteria. A criterion represents the
importance of a task. Each of these tasks is assigned a specific start
priority. Priority management assures that no task is lost. The highest
priorities are processed first. These priorities have nothing in common
with the priority management (PCS manual). The indicated packet lengths
refer to words, including header. Data word 13 is used to prevent
transmission of specific data words (PCS manual).
The tasks are listed below in detail:
TASK PRIOR. LENGTH START CRITERION
1. Write keyboard status 8 3 When pressing or releasing a key
2. Reset message bit 7 2 Press CLR for delete behavior 2
3. Write PLC setpoint 6 2..3 Always after changing a setpoint variable and
leaving the entry field
4. Read actual values 5 2..24*) In priorities 0..6, 12 continuously, otherwise when
display is refreshed
5. Read message bits 4 9 max. Continuously
6. Send PCS status 4 5 After changes
7. Read LEDs, flashing LEDs, 3 4 Continuously (menu selections only if the
memory and display temporary buffer is empty)
behavior
8. Read command word 3 3 Continuously
*) Depends on the number of variables displayed and if the addresses
are adjacent. If the addresses are not adjacent, one header is required
per non-adjacent variable (1 word).
Data transfer procedure When communicating with each other the PCS operates as master (AST).