Setra System Model 470 - Manual (Page 17)

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5. Transmit the new low setpoint, followed by S.
6. The 470 responds “PROTEC”. Set the program enable switch to “OFF”
(Section 7.2). Transmit C, for CLEAR.
7. To examine the current value of the setpoints, transmit SP, for a SETUP summary report
(Section 4.10).
For example, to set the high setpoint to 15.0010 and low setpoint to 14.0010, transmit:
SA15.0010S14.0010S
4.7 Setting and Checking Alarm Setpoints in Volatile Memory
As in the previous section, 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. This function changes the setpoints in volatile memory only. On power-up, the setpoints
default to the values stored in nonvolatile memory by use of the SETUP SETPOINTS function
(Section 4.6).
The new setpoints being transmitted to the Setra 470 must be in the engineering units currently in
use by the Setra 470. The new setpoints must be set within the factory setting of 105% of the
pressure range (high setpoint), and 5% below the pressure range (low setpoint).
To set new high and low setpoints, follow this procedure:
1. Transmit RSA, for RAM SETUP SETPOINTS.
2. Transmit the new high setpoint, followed by S.
3. Transmit the new low setpoint, followed by S.
4. To examine the current value of the setpoints, transmit SP, for a SETUP summary report
(Section 4.10).
For example, to set the high setpoint to 15.0010 and low setpoint to 14.0010, transmit:
RSA15.0010S14.0010S
4.8 Using the Tare and Zero Function
You can monitor changes in pressure relative to a known starting point with the TARE and ZERO
function in the Setra 470. It sets the current reading to zero or adds or subtracts a specified
offset to the reading. This is done by creating a tare value which is subtracted before data is
reported. On power-up, the tare values are set to 0.
1. To set the reading to zero, transmit Z, for ZERO. The transducer saves the current
reading as the tare value, and subtracts that value from every subsequent reading before
reporting it.
2. To subtract an offset from the reading, transmit the amount of the offset followed by Z, for
ZERO. The Setra 470 saves the offset as a tare value and subtracts it from every subse-
quent reading.