C |
Assigning I/O References for the Remote I/O Scanner
The discrete and analog I/O references that will be used by the Remote I/O Scanner must be configured. A starting address and length must be specified for at least one of the following:
H%I the discrete input table
H%Q the discrete output table
H%AI the analog input table
H%AQ the analog output table
For each table used, a contiguous block of references must be assigned. The reference addresses and lengths entered here normally include all the references actually used by the I/O modules located in the remote drop. If you need more information about references and memory usage in the Remote I/O Scanner, please refer to chapter 3.
For each memory type, the configuration screen automatically displays the next available beginning address, and a length. For %I and %Q memory, the LENGTH shown is in bits (points). Bit memories must be assigned on byte boundaries. For %AI and %AQ memory, the length shown is in words (each word is two bytes). The default length for all four memory types is 0. Each remote drop can have any mix of discrete and analog inputs up to 128 bytes, and any mix of discrete and analog outputs up to 128 bytes. The length limits reflect the maximum amount of data that can be sent on the Genius bus in a single transmission.
The beginning address defaults to 00001 only for the first drop whose configuration is entered. The Logicmaster 90±70 software will automatically increment the starting reference for successive drops, and when other devices are assigned. If the system has multiple remote drops, proper documentation of reference assignments will make configuration easier.
It is not necessary to allocate all four classes of I/O. To move on without assigning a class, leave the length set to 0. The starting references associated with that class will become meaningless (the display stays the same however). The same starting reference will be usable in the next remote drop (or any other device).
If you plan to expand a remote drop at a later date, the overall use of I/O references should be planned at this point. Since remote drops must use contiguous sections in each I/O table, add in the extra I/O space now, otherwise force Logicmaster 90 to leave the required I/O space free.
138 | Series 90±70 Remote I/O Scanner User's Manual ± July 1992 |
