Data Receive And Read; Data Send And Write; Scan Information Map - Toshiba V Series User Manual

Also note that you cannot issue TcnSccSetCycle or TcnScmSetTalkerBlk during
scan transmission. Issuing them will not cause an error, but there is no
guarantee that the setting will be reflected and in some cases, scan
transmission may stop working properly. When resetting the scan
transmission cycle or scan talker block, be sure to stop scan transmission first
and then restart it after resetting.
6.2.2

Data Receive and Read

The scan data sent periodically from other station is automatically stored in scan memory
within the JTNI card. One scan block is 128 bytes.
Consider the case of accessing a data in a scan block that is talker set by a controller. If
the controller sends the scan block no. 100, you must specify the offset 3200H (100 x
128) in order to access this data.
When a JTNI card enters a logical ring, it automatically starts receiving scan data.
TcnScmRead is used to read the scan memory. The offset and size of the scan memory
must be on 4 byte boundary.
6.2.3

Data Send and Write

When scan transmission setup is completed and transmission is started with
TcnSccSetControl, a talker set scan block is sent for each set scan cycle. To update the
transmission data, write the data in the scan block with TcnScmWrite. As with data read,
the offset and size of the scan address must be on 4 byte boundary.
6.2.4

Scan Information Map

The scan healthy map, scan unhealthy map, and scan talker map are available as scan
transmission related maps.
The scan healthy map represents the receive status of the current scan block with a
single bit. A healthy block is represented by 1 and an unhealthy block is represented by
0.
The scan unhealthy map shows blocks that were once healthy, but were subsequently
judged as unhealthy, even if only once. A 1 is set for unhealthy blocks. The scan
unhealthy map retains its values until they are cleared from an application program.
TcnScmClrUnHealthyMap is used to clear the scan unhealthy map.
The scan talker map contains the talker information of each scan block. It contains the
talker station address set in each scan block.
If a scan block is registered by more than one station, the scan talker map for that scan
block contains the station address of the duplicate stations in the High byte. To free
duplicate blocks, you must re-register the scan talker block of the duplicate stations. The
duplicate block information set in the High byte of the scan talker map is retained until it is
cleared from an application program. Duplicate blocks are cleared with
TcnScmClrTalkerMap.
Figure 6-1 and Figure 6-2 show the organization of each map.
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6.2 Scan Transmission
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