已截获RCA2 系列驱动器写定长运行指令信息。分别为0.5mm,0.1mm,0.03mm正向运行指令，求高手帮忙指出左后4个字节校验码如何计算？
0.5mm
01 17 90 00 00 1C 0F 00 00 14 28 00 00 00 32 00 00 4E 20 00 00 00 1E 00 00 00 1E 00 00 00 0A 00 59 01 7E 00 00 00 08 00 00 00 00 00 00 00 00 00 00 00 00 21 22
0.1mm
01 17 90 00 00 1C 0F 00 00 14 28 00 00 00 0A 00 00 4E 20 00 00 00 1E 00 00 00 1E 00 00 00 0A 00 59 01 7E 00 00 00 08 00 00 00 00 00 00 00 00 00 00 00 00 AA E0
0.03mm
01 17 90 00 00 1C 0F 00 00 14 28 00 00 00 03 00 00 4E 20 00 00 00 1E 00 00 00 1E 00 00 00 0A 00 59 01 7E 00 00 00 08 00 00 00 00 00 00 00 00 00 00 00 00 59 B0

这是用超级终端扑捉的吧，还是找通讯协议去吧，按modbus ASC算了一个,对不上，是算错了还是不对不知道，找协议吧。