ECAT SYS front ends do not have dcuid defined in the NAME_DCU_ID epics record
From bugzilla ticket #1026
Dave 2016-06-23 11:17:10 PDT
each front end reports its DCU id using an epics record called NAME_DCU_ID. For the ECAT SYS front ends this record has a zero value.
e.g. caget H1:SYS-ECATC1PLC1SDF_DCU_ID H1:SYS-ECATC1PLC1SDF_DCU_ID 0