Driver Manual
4.4.8Map Descriptor: Example 3 – Writing multiple points using one message.
Map_Descriptor_Name, Data_Array_Name , Data_Array_Offset, Function, | node_name, Address, Length, | DA_Field | , DA_Assoc, Scan_Interval | ||||
Write_MapDesc_1, DA_ SETPOINTS, 0 | , wrbc, | unit1 , | 0 | 1 , | nom_h_setpt , 2 | , 120.0s | |
Write_MapDesc_1, DA_SETPOINTS , 1 | , passive, | unit1 , | 0 | 1 , | t_setpt | , 2 |
|
A 'Write' and a passive to the same node. This write will update two fields, the nom_h_setpt and the t_setpt.
The write MapDesc. Must precede the passive.
This method is only appropriate if you plan to continuosly write to the devices. If you intend to write on change using the wrbx function then use multiple map descriptors that are not associated and give each one a wrbx.
Associate the passive map descriptor to the active (wrbc) map descriptor. In this way the driver will use only one message to write to the device. The message will be built using both map descriptors. This method reduces the communication load.
The association is made using the DA_Assoc parameter. Use unique positive integers. Omitting the DA_Assoc parameter when using ‘passive’ map descriptors will produce ambiguous results.
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