ProSoft Technology MVI56-AFC - Manual (Page 128)

Events MVI56-AFC ♦ ControlLogix Platform
User Manual Liquid and Gas Flow Computer
Page 128 of 316 ProSoft Technology, Inc.
February 25, 2011
Primary Slave Elements
These elements comprise configuration and status items required for the
implementation, as well as the Log-Download Window (LDW) itself. If a host
must access only the Virtual Slave for a log-download session, these points can
be mapped to the Virtual Slave using the existing mapping functionality. As
accesses to the LDW are severely restricted (every Modbus transaction to the
LDW must be addressed to offset 0 of the LDW), a shortcut mapping is available
that maps the entire LDW with a single data point.
Log-Download Window (LDW) Allocation
This is a block of 116 registers beginning at Primary Slave holding register 65400
and having a predefined layout. See Section 6 for the layout of this window. See
Section 4 for how this window, when mapped to the Virtual Slave, is coordinated
with other components of the Virtual Slave.
Site Configuration Items
1 Event Log Download Session Timeout Configuration word at Ph00146. This
timeout is in seconds, which must be at least 5 and may not exceed 300 (5
minutes). Default value is 60 (1 minute).
2 Virtual Slave LDW Location Configuration word at Ph00147. This is the
address in the Virtual Slave’s holding register bank of the first register of the
LDW. This value need not be limited to the 9900-register range of the
mappable Virtual Slave but may be located anywhere in the Virtual Slave’s
address space from register 100 up to 65420 (which address places the last
register of the LDW, at offset 115, at Virtual Slave register 65535). If this
value is 0, the LDW is not available in the Virtual Slave (a conventionally
mapped LDW is not visible).
Status
Event Log Download Active Session Map
Byte at Ph00007H (same word as Ph00007L, "PLC Offline Code").
This byte, previously unallocated, is a bitmap of the ports that currently have
event-log download sessions active. Bits are numbered by the 1-based port
number (where "Port #0" is the backplane), so that, for example, if a session is
active on Port #2, the middle of the three front-panel ports, bit 2 of Ph00007H is
set. The relevant bit is set when a download session is opened by the Setup
phase, and is cleared when the session is committed by the Completion phase or
when it is abandoned by timeout or explicit command. This byte Ph00007H is
already available in the premapped portion of the Virtual Slave at Vh00007H.