
UM344-2 APPENDIX A - FUNCTION BLOCK DESCRIPTIONS
September 1995
A.5 ALARM BLOCK
Alarm 1 ............................................................ Enable/Disable
Alarm 1 Setpoint .......................................... -999999 to 999999
Alarm 1 Type .......................................................... High/Low
Alarm 2 ............................................................ Enable/Disable
Alarm 2 Setpoint .......................................... -999999 to 999999
Alarm 2 Type .......................................................... High/Low
Self Clearing NAKS..................................................... On/Off
Alarms Out Of Service ................................................. On/Off
This function block includes 2 absolute alarms. The action of these alarms can be selected as HI or LO.
The setpoint for the alarms is entered in the units selected in the operator display block.
The Not Acknowledge bit (NAK) in the alarm status word is set whenever the alarm goes from a no-
alarm to an ALARM condition. When the ALARM condition clears, the NAK bit will reset if the Self
Clearing NAKS paramter is set to ON. If the Self Clearing NAKS parameter is set to OFF, then the
NAK but must be reset via a HART command.
The Alarms Out of Service parameter determines if the out of service bit in the alarm status word is set.
A.6 SETPOINT TRACK AND HOLD BLOCK
Tracking Setpoint ........................................................ Yes/No
Power-Up Setpoint ...................................... -999999 to 999999
This function block is a setpoint track and hold block and its
operating value can be changed from the pushbuttons of the XTC or
from the CHANGE SP key of the MXC. This function block can be
configured as tracking or non-tracking. If it is configured as
tracking, the SP will track the PV when the controller is in manual.
If it is configured as non-tracking the SP will remain at its hold value.
On power-up, the operating value in the function block is initialized to the Power-Up value. The Power-
Up value can only be changed by editing the parameter in this function block with the MXC or by storing a
new value via the pushbuttons of the XTC.
A.7 A/M TRANSFER BLOCK
Power-Up Mode ......................................... Automatic/Manual
Automatic Mode Only ................................................. Yes/No
Power-Up Valve ................................................. -1.0 to 110%
The A/M transfer function block consists of 1 Single Pole/Double
Throw switch. The switch is controlled with the pushbuttons of the
XTC or from the A/M key of the MXC. When the block is in
AUTO, the output is equal to the controller output. When the block
Absolute Alarm #1
Absolute Alarm #2
Alarm
PV
SP Track and Hold
Output
SP Track and Hold
PV
Output
M
A/M Transfer
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