Eurotherm 6100, Руководство пользователя

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100/180MM DISTRIBUTED GRAPHIC RECORDER: USER GUIDE
Page 122 HA029324
Issue 11 Oct 14
4.3.11 FUNCTION (Cont.)
GROUP MINIMUM
The following description assumes a group name of ‘Furnace 1’, which contains four channels with de-
scriptors ‘Temp 1’, ‘Temp 2’, ‘Temp 3’ and ‘Temp 4’
The output of the Group Minimum function is the current lowest value of any of the points in the source
group. The required source group is selected by picklist. Should a point return a non-valid value, it is
excluded from the calculation, and the result of the function is the minimum of the remaining points.
DESCRIPTORS
As a part of the Group Minimum function confi guration, it is possible to select one of two types of de-
scriptor: ‘User Defi ned’ and ‘Minimum Channel’. Figure 4.3.11u, below shows the relevant area of the
confi guration page.
Maths Number
Value
Function
Source
Units
Descriptor type
Descriptor
Maths Number
Value
Function
Source
Units
Descriptor type
Descriptor
User entered
descriptor
Descriptor of channel
with lowest current value
1) Furnace 1 min temp
Value
Group Minimum
1) Furnace 1
Furnace 1 min temp
User defined descriptor
1) Group 1 minimum
234.67
Group Minimum
1) Furnace 1
Minimum Channel Descriptor
Temp 1
Figure 4.3.11u Group minimum confi guration page
User Defi ned Descriptor.
This allows a descriptor to be entered in the normal way. For example ‘Furnace 1 min temp’. This de-
scriptor is copied to the Maths Number fi eld at the top of the display page.
Minimum Channel Descriptor
This selection causes the descriptor of the point with the instantaneous current lowest value in the group,
to become the (non-editable) maths channel descriptor. For example if the four channels in the group
(Temp 1 to Temp 4) have the instantaneous values 800, 950, 790 and 873 respectively, then the Descrip-
tor will be ‘Temp 3’ . Should Temp 3 rise above 800, whilst all the others remain static, then the Descrip-
tor would become ‘Temp 1’.
The ‘Maths Number’ fi eld which normally copies the maths channel descriptor, contains instead the text:
‘N) Group N minimum’, where ‘Group N’ is the default name of the source group.
A typical application of the ‘Minimum channel descriptor’ would be to include the descriptor in a mes-
sage sent to the chart on a regular basis by a Timer function.
Section 4.3.8 describes the entry of the
messages, and section 4.3.14 describes the setting up of timers.
(Continued)