Industrial communication networks - Fieldbus specifications - Part 6-21: Application layer protocol specification - Type 21 elements (IEC 61158-6-21:2019); English version EN IEC 61158-6-21:2019, only on CD-ROM
工业通信网络.现场总线规范.第6-21部分:应用层协议规范.21型元件(IEC 61158-6-21-2019);英语版本EN IEC 61158-6-21:2019 仅CD-ROM