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EXCEL 50/100/500/600/800 ATTRIBUTES
EN2B-0092GE51 R0512
23
Broadcast Hysteresis
Broadcast hysteresis (V1.5.x) The attribute "Broadcast Hysteresis" is available for the datapoint type "Global
Analog". The attribute "Broadcast Hysteresis" prevents new values from being
broadcast to other controllers unless the datapoint value changes (positively or
negatively) at least by the amount specified in the attribute "Broadcast Hysteresis".
The minimum hysteresis value is 10
-a
(a = number of decimal places set in the
attribute "Engineering Unit"), but not smaller than 0.2 (see also the example
in
section "
Value Hysteresis" on page 35). The CARE default value (i.e. 1% of actual
value and no less than 0.2) for this attribute is 0. Access to the attribute "Alarm
Hysteresis" is also possible via RIA/WIA.
This value can be edited from an operator interface (XI581 [not with XCL5010,
Excel 100C], XI582, XL-Online, and Excel 50 MMI) via the B port (XC5010C /
XC6010) or the serial port (Excel 100C, Excel 500), the system bus (XBS 1.3.3 and
higher and XFI 1.6.1 and higher), and CARE RIA/WIA statements. The password
level for this attribute is determined by the "Access" attribute (default initialization
value in CARE is 0). If several global points (remote points) are assigned to the
same physical point, the lowest global point "Broadcast Hysteresis" value of all
assigned global points is used.
Intrinsic Hysteresis for Analog Input Signals
A minimum default hysteresis of 37 mV (24 - 1 bit) for 0 to 10 V input signals is
implemented. Due to the nonlinearity of NTC sensors, the hysteresis varies over the
temperature range, whereas it is approximately constant for PT 100/1000/3000 and
Balco 500 sensors. Approximations of hysteresis depending on the sensor and
temperature range are summarized below.
NOTE The Intrinsic Hysteresis for analog input signals is not a user-
programmable attribute, but rather an intrinsic hysteresis of the Excel
50/100/500/600/800.
NTC 20k Ω Hysteresis varies nonlinearly over the entire temperature range and depending on
whether the upper boundary (MAX LIMIT) or the lower boundary (MIN LIMIT) is
exceeded. The approximations shown in
Table 8 can be used in practice
(intermediate values can be interpolated):
Table 8. Intrinsic hysteresis values for various temperature ranges
temperature range
average hysteresis
MIN LIMIT
average hysteresis
MAX LIMIT
-40 °C (-40 °F) 2.2 K (4.0 °F) 2.5 K (4.5 °F)
-30 °C (-22 °F) 1.3 K (2.3 °F) 1.3 K (2.3 °F)
0 °C (32 °F) 0.4 K (0.7 °F) 0.4 K (0.7 °F)
40 °C(104 °F) 0.5 K (0.9 °F) 0.4 K (0.7 °F)
80 °C (40 °F) 1.5 K (2.7 °F) 1.5 K (2.7 °F)
100 °C (212 °F) 3.0 K (5.4 °F) 2.7 K (4.9 °F)
130 °C (266 °F) 8.5 K (15.3 °F) 7.2 K (13.0 °F)
PT 100 (not with Excel 100C) Hysteresis increases approx. linearly with temperature.
Average hysteresis: 0.75 K (1.35 °F)
Hyst. At -45 °C (-49 °F): 0.7 K (1.3 °F)
Hyst. At 145 °C (293 °F): 0.8 K (1.4 °F)
PT 1000/1 Hysteresis increases approx. linearly with temperature.
Average hysteresis: 0.8 K (1.4 °F)
Hyst. At -45 °C (-49 °F): 0.7 K (1.3 °F)
Hyst. At 145 °C (293 °F): 0.9 K (1.6 °F)