不能是嵌套表达式的一部分。关于PAC系统内置函数，参考第八章”指令设定参考”。调用某些函数，如通讯请求(COMM_ REQ)，需要使用命令块或者参数块。对于这些函数，首先声明数组，在逻辑内进行初始化，然后作为一个参数传给函数。
Balluff Adapter Cable BKS-S32-S50 #17449
Rees Double Plunger Pushbutton 01968-032 #32461
Pall Industrial RC771BZ090H Pressure Switch #32671
Yuken Directional Valve DCG-03-2B3-5029 #13487
Fanuc I/O Expansion Unit A03B-0808-C200 #33313
Allen Bradley I/O Relay 1769-OW8 REV 2 Series B #17630
IFM DN0213 N600 Switching Amplifier #8528
Enidine Hydraulic Shock Absorber FP21294 #38809
Allen Bradley Contactor 500F-BO*930, 27Amp, #13695
Eagle Signal Programmable Timer CX901A6 #26277
TEC Time Delay Relay ER-31B #14513
Rees Red Pushbutton Heavy Duty 01968-032 #29259
Bosch Valve 0-811-145-116 #13271
Sperry Vickers Valve DGMFN 3 Y B2W 21 #13276
Whitlock PC Board Circuit Board 21511 #13046
Dwyer Differential Pressure Switch 1638 #22832
Square D Circuit Breaker FAL 34060 #13328
