IEC 60870-5-601 Ed. 1.0 (2006-06) Telecontrol equipment and systems - Part 5-601: Conformance test cases for the IEC 60870-5-101 companion standard

IEC 60870-5-104 Ed. 2.0 (2006-06) Telecontrol equipment and systems - Part 5-104: Transmission protocols - Network access for IEC 60870-5-101 using standard transport profiles

IEC 60870-5-6 Ed. 1.0 (2006-03) Telecontrol equipment and systems - Part 5-6: Guidelines for conformance testing for the IEC 60870-5 companion standards

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偶然，发现自己原来已经有IEC 60870-5-101 2003 edit 2.0.
哎，罪过，罪过！都是看不懂法文，我以为是法文文档呢，一直没看。

If the links from a central control station (controlling station) to several outstations (controlled stations) share a common physical channel, then these links must be operated in an unbalanced mode to avoid the possibility of more than one outstation attempting to transmit on the channel at the same time. The sequence in which the various outstations are granted access to transmit on the channel is then determined by an application layer procedure in the controlling station, see 6.2 in IEC 60870-5-5.

哎，能看原版就是不一样，有些问题一看知道，解析的比较到位。Edit 2.0比1.0解析的也清楚。
Polling方式下master必须等待slave的回答或超时，才能进行下轮通讯。无论下轮通讯是针对同一slave,还是另一个slave,必须等待上轮通讯的完结，完结的依据时slave回答获超时。规约明白规定，很清楚！！以前老是想找到证据，虽然这样想，但没人给我十分确定的回答，只是"可能"。

 FCB位针对每个slave的，一个slave一FCB，考虑翻转的问题就比较清楚了。