Siemens SIMATIC S7-300 Manual page 137

7.3.1 Activating the machine data
Overview
The checkback signal PARA notifies you that a DB-MD has been retained.
This machine data is automatically activated at power-up. The module's posi-
tioning functions are ready to operate.
If no DB-MD is present as yet on the FM 354 when the control is switched
on, the module can only communicate by way of the MPI interface. The con-
trol signals are not processed by the FM 354. Once an error-free DB-MD has
been transferred, the machine data is automatically activated, PARA is set
and the control signals are processed.
If the FM 354 is working with activated machine data, you can transfer a new
data block or individual parameters in modified form to the module, and if
the entire DB-MD is error-free this new data can then be put into effect by
way of the "Activate machine data" function.
The following approaches are possible:
FM 354 Servo Drive Positioning Module
If only E data have been modified in the machine data record since the
last activation, the equipment is activated with module status "Operation
in progress" = 0, without interrupting the servo cycle. "SYN" is retained.
If K data has also been modified in the machine data record since the last
activation, activation takes place with module status "Operation in prog-
ress" = 0 by way of a cold restart of the servo, just as occurs for a pow-
er-up of the module. The instantaneous actual position is still displayed,
but encoder pulses from incremental encoders might go unrecorded.
"SYN" is reset.
If the machine data record contains erroneous data at activation time, the
function is rejected, with the "Machine data cannot be activated" error
message (see Table 11-5, Class 2, No. 21).
Starting up the FM 354
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