100/180 mm PAPERLESS GRAPHIC RECORDER: USER GUIDE
User Guide
Page 111
HA028910
Issue 13 Sep 16
4.3.11 FUNCTION (Cont.)
Log Base 10
Takes log
10
of selected input. (For example: Input = 2 gives maths function value =
0.3010)
Log Base e
Takes log
e
of selected input. (For example: Input = 2 gives maths function value =
0.6931)
e to the power
Takes natural antilog of input. (For example: Input = 0.6931 gives maths function
value = 2)
Modulus
This function copies the magnitude of the input value, without the sign. For example,
the modulus of value +100 = +100; the modulus of -100 = +100.
Channel Maximum Maths function value is the minimum value the input point has reached since last
reset. When reset, the value is reset to the current input value.
Channel Minimum Maths function value is the minimum value the input point has reached since last
reset. When reset, the value is reset to the current input value.
Channel Average Takes the average value of the selected channel over a specifi ed time period. The
time period must be a multiple of 125 msecs. For example, a period of 0.2 seconds
would be rejected, but a period of 0.25 seconds would be accepted.
Master comms
Allows a maths channel to read point values from other instruments on the Modbus
link.
If virtual channels are used - see
section 4.3.22
.
Rate of change
Produces a value for the speed at which a signal changes over a specifi ed period.
O2 Correction
This function carries out O
2
correction of gas measurements for use in Continuous
Emissions Monitoring applications.
Relative Humidity
This uses wet and dry bulb temperatures and atmospheric pressure inputs to pro-
duce a percentage Relative Humidity reading.
Zirconia probe
Allows oxygen concentration and oxygen potential to be determined by solving the
Nernst oxygen equation.
Timestamp
When triggered by an event or alarm job, this causes the current number of millisec-
onds since 00:00 hrs on 1st January 1970 to appear as the function value. If the se-
lected PV format is date or time, the result is displayed as date or time, respectively.
Confi g Revision Number*
Allows the Confi guration Revision number to be used as the input to a maths chan-
nel. When this maths channel is included in a group, the user can determine the
Confi guration Revision number obtaining at any time in the history record.
Security Revision Number*
Allows the Security Revision number to be used as the input to a maths channel.
When this maths channel is included in a group, the user can determine the Security
Revision number obtaining at any time in the history record.
*Note: See ‘About’ in
section 4.6
for a description of the Confi guration and Security Revision num-
bers.
Thermocouple Cal Correction
Defi nes correction points allowing offsets to be added to channel inputs to compen-
sate (for example) for equipment errors.
SCALE LOW / SCALE HIGH
The ‘zero’ and full scale values for the maths function, as displayed. If A/B switching is enabled, a second
set of scale low and scale high values can be entered. ‘A’ values are used during normal operation. ‘B’
values are switched to by job action, as described in
section 4.7
.
