PLC单元常量
在本节中：
SYS_UNIT_INVALID
SYS_UNIT_AFP7CPS4E
SYS_UNIT_AFP7CPS3E
SYS_UNIT_AFP7CPS3
SYS_UNIT_AFP7CPS4RE_CPS41E
SYS_UNIT_AFP7CPS3RE_CPS31E
SYS_UNIT_AFP7CPS3R_CPS31
SYS_UNIT_AFP7CPS4RES_CPS41ES
SYS_UNIT_AFP7CPS3RES_CPS31ES
SYS_UNIT_AFP7CPS3RS_CPS31S
SYS_UNIT_AFP7CPS2R_CPS21
SYS_UNIT_AFP7CPS41ET5
SYS_UNIT_UELC500
SYS_UNIT_AFP7X16DW
SYS_UNIT_AFP7X32D2
SYS_UNIT_AFP7X64D2
SYS_UNIT_AFP7Y16R
SYS_UNIT_AFP7Y16T
SYS_UNIT_AFP7Y32T
SYS_UNIT_AFP7Y64T
SYS_UNIT_AFP7Y16P
SYS_UNIT_AFP7Y32P
SYS_UNIT_AFP7Y64P
SYS_UNIT_AFP7XY64D2T
SYS_UNIT_AFP7XY64D2P
SYS_UNIT_AFP7PXY001
SYS_UNIT_AFP7AD4H
SYS_UNIT_AFP7AD8
SYS_UNIT_AFP7DA4H
SYS_UNIT_AFP7TC8
SYS_UNIT_AFP7RTD8
SYS_UNIT_AFP7PG02T
SYS_UNIT_AFP7PG04T
SYS_UNIT_AFP7PG02L
SYS_UNIT_AFP7PG04L
SYS_UNIT_AFP7PP02T
SYS_UNIT_AFP7PP04T
SYS_UNIT_AFP7PP02L
SYS_UNIT_AFP7PP04L
SYS_UNIT_AFP7NSCR_NSC
SYS_UNIT_AFP7PHLSM
SYS_UNIT_AFP7NPFBM
SYS_UNIT_AFP7NDNM
SYS_UNIT_AFP7NCANM
SYS_UNIT_AFP7NPFNM
SYS_UNIT_SL_VFP7
SYS_UNIT_AFP7HSC2T
SYS_UNIT_AFP7HSC4T
SYS_UNIT_AFP7MXY32DWD
SYS_UNIT_AFP7MXY32DWDH
SYS_UNIT_AFP7MC16EC
SYS_UNIT_AFP7MC32EC
SYS_UNIT_AFP7MC64EC
SYS_UNIT_AFP7MW_F
SYS_UNIT_AFP7MW_W2
SYS_UNIT_AFP7MW_W