Siemens 7MB1420, Instruction Manual, Page: 21 / 74

Fig. 7.1 Timing of automatic calibration procedure ("autocal")
The following points must be observed when using the automatic calibration:
Calibration gas 1 is used for all measuring ranges if only one calibration gas is connected or if
function 17 is set to total calibration in the case of two through four calibration gases.
The measuring ranges 1, 2, 3 and 4 are calibrated using the calibration gases 1, 2, 3 and 4 if four
calibration gases are connected and function 17 set to individual calibration. The assignment
between calibration gas 1 and measuring range 1, calibration gas 2 and measuring range 2 etc.
must be observed.
The floating changeover contact “Calibration/Measurement” signals “Calibration” during the pro-
cedure.
In systems with several devices, one analyzer can assume a master function. The signal contact
“End of calibration” closes for five seconds at the end of the calibration cycle. This contact can start
the automatic calibration procedure for a second device. The second analyzer then has a slave
function; the automatic calibration must be switched off for this analyzer using function 22,
identifier 0.
Set time up to first automatic
calibration (function 41)
LED “autocal” flashes
LED “not ready” lights up
Purging time
Purging time
Zero gas valve opens, signal
contact “Start calibration”
Function 44,
identifier
(Possibly 3, 4, 5)
Function 44,
identifier 1
Calibration
Zero gas
purging
Calibration
gas
(possibly
1, 2, 3, 4)
A
Zero point being calibrated
Zero gas valve closes;
Calibration gas valve
opens
Set time between two automatic
calibration procedures (function 42)
Longest time entered
under function 44
Span being calibrated
Calibration gas valve closes
Operation
with
sample
gas flow
Sample
gas
pre-
purging Purging time
Signal contact “End of
calibration procedure”
Sample
gas
mode
End
Start
Calibration
21