Parameterizing
3.3 Presence check and MDS control
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Function manual, Release 03/2006 , J31069-D0167-U001-A2-7618
3.3
3.3
Presence check and MDS control
Various operating modes can be parameterized for MDS control (with parameter
MDS_control).
The exact interaction between these modes for the following components:
•
Presence check
•
MDS control
•
Next command
is described in this chapter. In its default state, the ASM uses presence check and no MDS
control.
Presence check
The presence check is a piece of logic in the MOBY-ASM's firmware which recognizes
whether a mobile data memory is in the transmission window of the write/read device. It can
be controlled with various mechanisms. The selection is performed with parameter
MDS_control. A mechanism is currently available.
Field scanning (MDS_control = 1, 2):
The ASM's firmware continuously scans its surroundings via the magnetic field to determine
whether a mobile data memory is present. A hysteresis during field scanning suppresses
most of the switching back and forth of ANZ_MDS_present when a mobile data memory
stops on the border of the field.
Presence
A mobile data memory is located in the field of the write/read device. The presence bit
(ANZ_MDS_present in command and status word) is set (see Section "Command and status
word). The presence display is usually implemented via the PRE LED on the front of the
ASM (see Section "Brief description of ASM hardware").
MDS control
MDS control is turned on when "MDS_control = 2" is set. MDS control is an option of the
firmware of the ASM. It synchronizes the MDSs in the material flow with the user program. It
supplies an error message when synchronization is lost.
The following are considered asynchronous.
•
MDS whose command was not fully processed by the ASM leaves the transmission
window.
•
MDS which is moving through the transmissionn window but is not processed by the user
program.
An enabled MDS conrtol forces use of the NEXT command in the application.