当有数据通过PLC电源模板上的SNP串口连接器传输数据时灯会闪烁，并且当串口不工作时熄灭.(在一些较早的364型CPU产品中，该发光二极管被计为“SNP”)所有的系列90-30 CPU均有这个标准的串口.
ELDEC 5060044 USPP 5060044
RELIANCE ELECTRIC 45C-37B NSFP 45C37B
FANUC A06B-0642-B011 USPP A06B0642B011
OMRON C200HW-PCU01 NSFP C200HWPCU01
ELO TOUCH SYSTEMS E286569 FNFP E286569
GE FANUC 44A399785-G02 USPP 44A399785G02
ALLEN BRADLEY PC-128-0790 USPP PC1280790
ASEA BROWN BOVERI 8R37-1041-31-31?01 USPP 8R371041313101
FANUC A06B-6110-H006 USPP A06B6110H006
FANUC A06B-6058-H011 NSPP A06B6058H011
ALLEN BRADLEY 1336S-B015-AA-E?N-HA1-L5 USPP 1336SB015AAE
MARPOSS 6315060700 NSPP 6315060700
JOHN CRANE 35113162 NSFP 35113162
TELEMECANIQUE TSX-RPM-64-16 NSFP TSXRPM6416
WESTINGHOUSE MCG3800F USPP MCG3800F
NEMATRON CORP IC5031-743001E0 USPP IC5031743001E0
