FieldServer Optomux FS-8700-17 - Manual (Page 15)

FS-8700-17_Opto22.doc Manual Page 13 of 24
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Appendix A.1.4. Map Descript or Example – Triggered A ction
This example shows the elements necessary to generate a triggered poll. Even though this Map Descriptor appears to write to the device continuously the driver
recognizes the Opto22_Trigger parameter and based on its value will only send the poll when the trigger value is set.
The driver processes the Map Descriptor at the scan interval specified. Each time that it is processed the driver checks the element of the Da_Byte_Name Data
Array specified. If the value of the 1
st element of array located at Data_Array_offset = 1 then the driver executes the command. If the value is not =1. then the
driver ignores the Map Descriptor.
If the Map Descriptor is triggered then the driver will write a response status to the same data element on completion of the poll. Thus the value of 1 will be set to
zero for success or some other value indicating an error.
Map_Descriptor_Name , Data_Array_Name , Data_Array_Offset , Function , Node_Name , Length , Scan_Interval , Opto22_Function , Opto22_Trigger , DA_Byte_Name
DEVICE77_STAT , CNTR_POSNS , 0 , Wrbc , DEV77 , 16 , 0.2s , CLEAR COUNTERS ,Yes , COMMAND_ARRAY
This Map Descriptor
is processed as a
write command and
will be processed
continuously.
The driver will check to see if a
trigger has been set every 0.2
seconds. This keyword value for the
opto22_trigger parameter tells
the driver only to send this
Optomux command if it has been
triggered.
When this parameter is used the
DA_Byte_Name parameter must
also be used. This is the name of a data array whose
contents will be used to trigger the
command.
The driver looks at the element found at
the Data_Array_Offset and if that value=1
then the command is sent. On
completion/error the driver will change
this value to some other number.