COMMUNICATION | EXCEL 50/100/500/600/800 |
Remote Trending (dial-up)
General
Per front-end (XBS, EBI), trend values for a total of 20 data points can be stored (via dial-up) in the remote trend buffer of the controller to which the modem has been connected. These 20 data points can come from the controller to which the modem has been connected, or they can come from various other controllers on the same C-Bus or LONWORKS bus.
Controller Firmware 2.03.xx and Higher
Per front-end (XBS, EBI), trend values for a total of 100 data points can be stored (via dial-up) in the remote trend buffer of the controller to which the modem has been connected. These 100 data points can come from the controller to which the modem has been connected, or they can come from various other controllers on the same C-Bus or LONWORKS bus. Unused application memory can be used as additional remote trend buffer.
Controller Firmware 2.04.xx and Higher
In combination with the large RAM controllers XD52-FC, XD52-FCS, XC5210C, a total of 384 KB of additional trend buffer is available. This increase in the trend buffer size reduces the number of times the controller must dial-up the front-end and lowers the risk of trend values being overwritten due to a full buffer.
By exploiting this feature, it is possible, when no application is downloaded, to use the EXCEL controller as a pure trending device.
The amount of additional memory available for the remote trend buffer is deter- mined by the value for “Application Memory Size” entered with the MMI during the start-up sequence of the controller. This number is subtracted from the total application memory, and the resulting number, in Kbytes, is the additional remote trend buffer size. Fig. 24 illustrates the adjustable remote trend buffer.
128 KB
TOTAL APPLICATION MEMORY
UNUSED APPLICATION MEMORY
e.g. 58 KB
APPLICATION
e.g. 70 KBYTES
REMOTE TREND BUFFER
58KB
=1263 ADDITIONAL TREND SAMPLES
+100 TREND SAMPLES (DEFAULT)
= 1363 T0TAL TREND SAMPLES
Fig. 24. Adjustable remote trend buffer example
The maximum number of trend values will be displayed on the MMI once a value for application memory size is entered. The adjustment range for the application memory size is the following:
Table 22. Adjustment range for application memory size
application memory size | trend values in remote trend buffer |
maximum (default): 128 Kbyte | 42 per front-end |
example: 120 Kbyte | 100 per front-end |
minimum: 38 Kbyte | 100 per front-end; PLUS “N” for front-end A |
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