Siemens simatic hmi op7, Equipment Manual

Page: 107 / 196

13-1
Equipment Manual OP7, OP17
Release 04/99
Controlling the OP from the PLC
The OP and the application program communicate with each other by alter-
nately reading from and writing to the data areas in the memory of the PLC.
Thus the PLC and the OP can make each other execute different actions by
evaluating data areas.
PLC jobs are functions that are initiated on the OP – for example, selecting
screens, printing screens, transferring the date and time from the OP to the
PLC. Jobs are stored with a job number and parameters on the PLC.
The PLC, for example, can call a screen on the OP to draw the operator’s
attention to a particular condition or to the fact that inputs are required.
You will find a complete list of all the PLC jobs with their parameters and a
description of all the data user areas that have to be configured on the PLC in
the Communication User’s Manual.
The LEDs on the function keys of the OP can be driven from within the PLC.
This means it is possible to signal to the operator by means of a lit key LED
that it is advisable to press a specific key in a certain situation.
For LED control, it is necessary to create an LED image on the PLC. In the
configuration, two bits are assigned to every LED in the LED image area.
These two bits can be used to implement four different LED states:
OP7 Off, Permanently On, Low-Speed Flashing, High-Speed Flashing.
OP17 Off, Green Permanently On, Red Permanently On, Red Flashing.
The OP stores information about the object type called in the screen number
area of the PLC. Thus it is possible for information about the current display
contents of the OP to be transferred to the application program on the PLC
and, from there, for certain reactions to be initiated – for example, calling
another screen.
Common data
areas
PLC jobs
LED control
Evaluating the
screen number
13