Emerson 54e pH/ORP Controller Mode Priority Chart, Condition Definitions, Action Definitions

MODEL 54e pH/ORP	SECTION 6.0
	THEORY OF OPERATION

6.8CONTROLLER MODE PRIORITY

Your Model 54e pH/ORP can function in different modes depending on both how it is configured, what process conditions exist, and actions an operator may have made. To reconcile these possible modes, there is a set priority that determines exactly what will happen to the 2 current outputs and the 4 alarm relays in the event of mul- tiple modes occurring at the same time. See Table 6-1 below.

Priority is in the following order (from lowest to highest): normal, fault, timer, hold, feed limit, test. Each output or relay acts as if it is only in the state of highest priority.

NOTE

Some of these features may not be in use for your con- troller.

TABLE 6-1. Controller Mode Priority Chart

Condition	Priority	Current	Current	Alarm	Alarm	Alarm	Alarm
		Output 1	Output 2	Relay 1	Relay 2	Relay 3	Relay 4
Normal	1	Normal	Normal	Normal	Normal	Normal	Open
Fault	2	Default	Default	Default	Default	Default	Closed
Interval Timer	3	Hold	Hold	Default/	Default/	Default/	Prior
				Normal1	Normal1	Normal1
Hold Mode	4	Hold	Hold	Default	Default	Default	Prior
Feed Limit	5	Normal	Normal	Open1	Open1	Open1	Closed
Simulate tests	6	Test1	Test1	Test1	Test1	Test1	Test1

1Indicates the state IF that item has been configured or selected (i.e. if it is an interval timer or a feed limit timer or it is the one being tested). Unconfigured or unselected items are not affected by that mode.

Condition Definitions:

1.Normal refers to conditions when no other mode is present.

2.Fault is when the instrument has diagnosed a fault condition. A fault message is displayed and the red LED will be on.

3.Interval Timer is only while the timer sequence is occurring.

4.Hold Mode is while hold is activated by the operator (i.e. during calibration).

5.Feed Limit occurs when a feed limit timer has reached it's limit and is turned off after being on for too long.

6.Simulate tests are described in Section 5.4.

Action Definitions:

1.Normal is determined by process conditions or how the item has been configured (Sections 5.5, 5.6)

2.Open is a deenergized alarm relay. (alarm off)

3.Default is the setting configured for each item if there is a fault. (Sections 5.5, 5.6)

4.Closed is an energized alarm relay. (alarm on)

5.Hold is the setting for the current output configured in Section 5.5 (this could be a fixed mA value or the last normal value)

6.Prior is the state the alarm had before that mode occurred.

7.Test is the value input by the operator (mA for current, on or off for a relay).

49