PLC的RS-422接口配接DB-25型连接器，而PC机一般用DB-9型连接器。硬件电路图如图1所示。
将RS-232的RS、CS短接，这样对计算机发送数据来说，PLC总是处于就绪状态。也就是说，计算机在任何时候都可以将数据送到PLC内。又由于DR、ER交叉连接，因此，对计算机接收数据来说，必须等待至PLC处于准备就绪状态。
2通信装置的软件描述
2.1 FX2系列PLC与计算机之间通信协议
FX2系列PLC与计算机之间的通信采用RS-232标准，其传输速率固定为9600bps，奇偶校验位采用偶校验。数据格式如图2所示。数据以帧为单位发送和接收。一个多字符帧由力所示的五部分组成，其中和校验值是将命令码ETX之间的的呢字符的ASCII码（十六进制数）相加，取得所得和的低二位数。STX和ETX分别表示该字符帧的起始标起和结束标志。
ABB Pole Transformer 34500GY/19920 277/480 500 kVA NEW
CH Westinghouse 1600 Amp 1600A A RDC316T33W 16RES16T
Westinghouse VCP-W 250 1200 Amp A 5kV Type50 3776A11G01
Zenith 1200 A Amp ZBTSD121E 480 V 3 PH Transfer Switch
US Electric Titan TE Motor 300 HP 1785 RPM 449TL 449T
Siemens 750kVA 13200/480Y/277V Padmount Transformer 3PH
Square D 750kVA 13200/480Y/277V Padmount Transformer
Cooper 0053LP12KZ5A 750 kVA 4160/2400 208/120 Padmount
Square D Magnum 15 kV 15-GSB-1-750-1200 Amp AM 13.8-500
Like New Condition GE Magnablast Vacuum Retrofit
ABB EMAX 600V SACE E4S-A 32 / E4S3200 3200Amp 3200A
Square D RJF36160U43A PowerPact RJ 1600 Amp A LSI NEW
Siemens SBS 2500 SBS 4025 SBS4025 F 2500 A Amp SB25TLSI
Allen Bradley AB 1336F-B060-AA-EN 60 HP 460V NIB New
GE AKR-7D-75 3200 A Amp Breaker RMS-9 MVT Trip LS 635 V
ITE Gould BBC ABB K1600 S K1600S 1600A Air Breaker LSIG
ITE GOULD BBC ABB K1600 K 1600 1600A Air Breaker LSIG
ITE Gould BBC ABB K1600 S K1600S 1600A Air Breaker LSIG
GE General Electric Power Vac VB1 13.8-750-3 PowerVac
ITE Circuit Breaker Type LG 3000 Amp A with AC-Pro Trip
Allen Bradley AB 1336S-B125-AN-EN-L6 125/150 HP Drive
Reliance 65C500/9101-2160 QUIQ Servo Positioning Module
Siemens SBS 2016 SBS2016 SBS2016DV 1600 Amp SB16TP02G
Siemens SBH 2016 SBH2016 SBH2016DV 1600 Amp SB16TP02G
Siemens SBH 2016 SBH2016 SBH2016DV 1600 Amp SB16TP02G
Square D 2500 Amp 2500A SE SEDG25E1C1T1G2 SED362500
Allen Bradley AB 150-A360NBRB SMC Plus 300HP Soft Start
GE Limitamp Multilin Starter 176 Amp 2.5 kV CR194A147B2
GE General Electric Power Vac VB1 4.16-250-3 PowerVac
Siemens 6SE7231-8EF00-3AB0-Z VT 125/150 HP VS AC Drive
Westinghouse PC 2000 Amp 2000A A PC32000WK 2000A
ITE Circuit Breaker Type LG 3000 Amp A Siemens RMS Trip
Square D NHL361200 NHL 1200 Amp A 1200A 600vac NIB
Allen Bradley AB 1336F-B050-AA-EN 50 HP VF VS Drive NIB
GE AKR-7D-100 4000 A Amp Low Voltage Air Breaker 635 V
Telemecanique Altivar 66 ATV66C19N4U AC Drive 200 HP
Hitran Transformer 550 kVA 575/460Y/266 V 460 Y 550kVA
GE AKR-10D-100 4000 A Amp Low Voltage Air Breaker 635V
Telemecanique Altivar 71 ATV71HC11N4 Drive 150HP/110kW
Waukesha 030U2AP 030 Positive Displacement PD Pump NEW
Westinghouse SPB 65 Disconnect Breaker Panel 1600 Amp A
Siemens Sikostart 3RW34 softstart starter 700A 300 HP
GE AKR-9D-100 4000 A Amp Low Voltage Air Breaker 635 V
Siemens Micromaster 440 6SE6440-2UD38-8FA1 125/150 HP
GE General Electric Power Vac VB1 4.16-250-2 PowerVac
Siemens ITE Sentron SHND69120ANGT 1200A 1200 Amp A
GE Power Break PowerBreak TPMMF86 3000 Amp 3000A A
