没连接面板OP77A之前，通讯和运行都正常，连接上OP77A后，CPU报系统故障，并且在运行情况下STOP灯亮，错误诊断信息为：
Event 1 of 10: Event ID 16# 2522
Area length error when reading
Global DB, bit access, Access address: 670
Requested OB: Programming error OB (OB121)
Priority class: 1
Internal error, Incoming event
06:57:12.191 PM 04/01/2010
vent 2 of 10: Event ID 16# 2522
Area length error when reading
Global DB, word access, Access address: 656
Requested OB: Programming error OB (OB121)
Priority class: 1
Internal error, Incoming event
06:57:12.191 PM 04/01/2010
希望高手能给解决