Panasonic FP2 ET-LAN Technical Manual page 246

[MD] Register or Reset data monitored
This registers data to be monitored. Up to 16 points can be registered for one unit.
Note:
If the data code is IX or IY, "0" should be specified for the four characters of the word number.
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Dummy registrations ("*") are not possible when registering data to be monitored.
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