它們以PRM操作數(shù)確定的基準(zhǔn)地址為起始值，必需的16位基準(zhǔn)地址數(shù)目取決于被請(qǐng)求的特別PLC服務(wù)類型.參數(shù)塊用于儲(chǔ)存功能塊的輸入和輸出量。SVC_ REQ傳遞能流，除非指定了錯(cuò)誤的功能塊數(shù),錯(cuò)誤的參數(shù)或超出范圍基準(zhǔn)地址。不同的特殊SVC_REQ功能有另外的引起失敗的原因

SQUARE D PKA36200G USPP PKA36200G

BALDOR D74CP NSPP D74CP

COMPUMOTOR PK-130 USPP PK130

ALLEN BRADLEY 284D-FVD2P3Z-10?-CR-3 NSFP 284DFVD2P3Z10CR?

DAWN INDUSTRIES VMERACK USPP VMERACK

INTERMEC 9181C02 USPP 9181C02

KLOCKNER MOELLER N121000CNA USPP N121000CNA

SICK OPTIC ELECTRONIC CLV-260A-0020 USPP CLV260A0020

MITSUBISHI A8GT-70GOT-SB USPP A8GT70GOTSB

CUTLER HAMMER ECN1801EJA NSFP ECN1801EJA

DAWN INDUSTRIES 11-1005686-03 USPP 11100568603

PARAGON C98043-A1220-L USPP C98043A1220L

YASKAWA ELECTRIC CACR-SR44BB1AM-?Y8 NSFP CACRSR44BB1AMY8

GE FANUC IC3600SPRF1 USPP IC3600SPRF1

RELIANCE ELECTRIC T18R1312M-KC USPP T18R1312MKC

FANUC A16B-2200-0843 USPP A16B22000843