Setra System Model 470 - Manual (Page 16)

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9. If the 470 responds “UNABLE”, the user defined units have been disabled by use of the
DISABLE UNITS function (Selection 5.3). Transmit C, for CLEAR, re-enable the user defined
units (Section 5.3) and restart this procedure from the beginning.
10. Transmit 5 alphanumeric characters, in any combination, to represent engineering units
of the conversion.
For example, if the transducer is currently reporting in PSI and the desired units are grams
per square centimeter, the ratio is 70.307 g/cm2 per psi (a multiplier). Transmit:
R70.307Ug/cm2
The Setra 470 unit will report in g/cm2 to an interrogation.
4.5 Tracking Min and Max Values
The Setra 470 tracks the minimum and maximum pressures applied to the sensor whenever the
MIN/MAX function is activated by the following procedure. On power-up the MIN/MAX function is
off.
1. To enter the tracking mode, transmit SM, for SETUP MIN/MAX.
2. To examine the recorded maximum and minimum values, transmit SP, for SETUP sum-
mary report ( Section 4.10).
3. To deactivate the min/max tracking mode, transmit -M, for MIN/MAX.
4.6 Setting and Checking Alarm Setpoints in Nonvolatile Memory
The Setra 470 has an alarm capability which indicates when the pressure applied to the sensor
has exceeded a high or a low setpoint. A message of “LO ALARM” or “HI ALARM” is reported
through the communications port when either situation occurs.
The factory setting for the high setpoint is 105% of the pressure range, and the low setpoint is 5%
below the pressure range. The new setpoints must be within this range, the unit will respond
“PROTEC” and then “UNABLE” if they are not in this range.
The new setpoints being transmitted to the Setra 470 must be in the engineering units currently in
use by the Setra 470. These alarm setpoints are saved in nonvolatile memory until new ones are
entered, even if the power is shut off and turned back on. These setpoints will be used by the
470 unless other setpoints are entered into volatile memory using the procedure in Section 4.7.
To set new high and low setpoints, follow this procedure:
1. Set the program enable switch to “ON” (Section 7.2).
2. Transmit SA , for SETUP SETPOINTS.
3. If the response “NO CAL” is received, the program enable switch specified in Step 1 is
not set to “ON” (Section 7.2). Transmit C, for CLEAR, and restart this procedure from the
beginning.
4. Transmit the new high setpoint, followed by S.