Instruction manual

10.0 OTHER FUNCTIONS SM425 INSTRUCTION MANUAL
These three modes each have the specific limitations described below:
• If “No Function” is selected: No blow back operations are executed.
• If “Semi-auto” is selected, semi-automatic blow back can be executed (but no calibration is made
even when the automatic calibration startup time is reached.)
• If “Auto” is selected, automatic blow back can be executed in either the “Auto” or “Semi-auto”
mode.
Use the following procedure to setup blow back operation:
1. Select the Setup key from the basic panel display screen to display the Execution/Setup display
screen. Then select Maintenance from the Execution/Setup display screen.
2. Select the Blow back setup from the Maintenance display screen and select Mode. The mode
selection display shown in Figure 10-8 appears.
Figure 10-8 Blow Back Setup Screen
10.2.1.2 Operation of Blow Back
Figure 10-9 shows a timing chart for the operation of blow back. To initiate blow back from a contact input
signal, use a contact input with an ON-time period of one to 11 seconds. Once blow back starts, a contact
output opens and closes at ten-second intervals during the preset blow back time. After the blow back
time elapses, the analog output remains held at the preset status until the hold time elapses (refer to
Section 1.46, earlier in this manual).
The hold (output stabilization) time is the time following the completion of blow back operations during
which the process gas returns to the sensor and sensor output returns to normal operating conditions.
42500001 REV A 161