ProSoft Technology PS-QS-1x10-0781 - Manual (Page 66)

FieldServer Configuration Manual Page 66 of 90
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10.3.5 Keepalive Map Descriptors
Keepalive Map Descriptors read data from all the Nodes every 60 seconds and act as a Keepalive signal. This is required for ascertaining cable status.
Example:
Consider two FieldServers connected in Hot Standby Mode 2, each with a SCADA Tier and a PEX Tier polling a two port PLC. The SCADA Tier of the FieldServer
receives data from the PEX Tier of the same FieldServer. If the SCADA Tier of the second FieldServer is not polling the PEX side on its own FieldServer then
there is no way that the second FieldServer can know when the cable connected to the PLC goes bad, and reflect the change in the corresponding Data Array.
Hence Keepalive Map Descriptors are required which check the cable status and eliminate this condition.
Data_Arrays
Data_Array_Name , Data_Format , Data_Array_Length
DA_Keepalive
, UINT16 , 6
Map_Descriptors
Map_Descriptor_Name , Data_Array_Name , Data_Array_Offset , Function , Node_Name , Address , Length , Scan_Interval
Keepalive_C01
, DA_Keepalive , 0 , Rdbc , TA_01 , 40001 , 1 , 60s
Keepalive_C02 , DA_Keepalive , 1 , Rdbc , TB_02 , 40001 , 1 , 60s
Keepalive_C03 , DA_Keepalive , 2 , Rdbc , TC_03 , 40001 , 1 , 60s
Keepalive_C06 , DA_Keepalive , 5 , Rdbc , TEG_S_06 , 40001 , 1 , 60s