A valve object shows its InTransit text whenever the OPEN and CLOSED state tags are equal: both on or both off. Both off at rest means missing feedback, both on means contradictory logic, and exactly one on with the wrong text means a mapping error in the project. Read both tags live, sort the case by the combination you see, and repair the signal or the mapping at its source.
A valve graphic object shows a third text whenever its two state inputs read the same: both on or both off. The text is worded InTransit, or in travel on some objects. The label is the object reporting that neither end state is confirmed, because a valve cannot be open and closed at once and cannot sit at a stop with neither switch made. The repair is never in the text field. Read the OPEN and CLOSED tags live, sort what you see into the four input combinations, and fix the missing or contradictory signal at the switch, the wiring, the input channel, the PLC logic or the project mapping. This page gives the rule the object follows, the symptom each combination produces, a worked diagnosis and the repair for each case.
The rule the two state tags follow
A valve object takes two boolean inputs, named OPEN and CLOSED in its tag fields. Four input combinations are possible, and the object folds them into three display conditions (On = 1, Off = 0):
| OPEN tag | CLOSED tag | Text the object shows |
|---|---|---|
| On | Off | Open |
| Off | On | Closed |
| Off | Off | InTransit |
| On | On | InTransit |
Two of the four combinations are valid positions, and the two invalid ones share one label. The label alone cannot tell you which fault is present; reading the two tags live is what separates missing feedback from contradictory feedback. One bit drives an indicator through two states, as show two text states on an HMI from one PLC bit covers; the second bit is what buys you the third condition and makes a valve symbol honest. The same idea, one display condition per valid combination, is how show three alarm states with one HMI indicator builds a three-state alarm banner.
Symptoms and what each points to
- Third text only while the valve travels, clearing at each stop. Normal operation. Both limit switches are off mid-travel and the arriving switch closes the feedback at the end. A valve that takes 30 seconds to stroke shows the third text for those 30 seconds and a confirmed position at each stop. Nothing to repair.
- Third text while the valve sits still. The pair reads equal at rest. Read both tags live to split missing feedback from contradictory logic.
- Both tags off at rest. Missing feedback. The fault sits in a limit switch, the field wiring, the input channel or the address the project reads, and the checks in the example below sort them in three steps.
- Both tags on at rest. Contradictory feedback. Something asserts both end states together: PLC logic that sets both bits, or two inputs fed from one device.
- Exactly one tag on, wrong text. Mapping or text assignment in the project: the open signal is assigned to the CLOSED field, or the two texts are swapped.
- Display frozen on one position whatever the valve does. Neither tag reaches the object. Check the live tag values first, then the communications path; trace the tag value path walks that check for indicator objects.
Read both tags live and sort the case
- Open the watch or online values view your HMI software provides and put the OPEN and CLOSED tags side by side.
- At each stop, command the valve to that end (closed at the closed stop, open at the open stop), let it settle for 10 seconds after the stroke finishes, and write down both values.
- Watch one full open-and-close cycle, about 60 seconds for a valve with a 30-second stroke in each direction, and note when the third text appears and clears.
Two stationary readings decide the case. Exactly one tag on at each stop, with the matching text, means the display logic is healthy. Both tags equal at a stop means a signal fault. One tag on with the wrong text means a mapping fault. Both tags should read off only mid-travel.
Example: a discharge valve sitting closed with both tags reading off
The inputs: OPEN tag = 0 (off) and CLOSED tag = 0 (off), read in the watch view. The valve is commanded closed and confirmed closed at the stop by hand. The feedback circuit is discrete, switching the 24 V DC signal level most control panels run their I/O at.
The rule in words: to log the pair as one number, encode combination = (2 × OPEN) + CLOSED. The object's rule puts combination 0 (both off) and combination 3 (both on) on the third text; combination 1 (open only) shows the open text and combination 2 (closed only) shows the closed text. The encoding is a logging aid; the object only compares its two inputs.
The arithmetic: with OPEN = 0 and CLOSED = 0, combination = (2 × 0) + 0 = 0, both off. A closed valve should read OPEN = 0 and CLOSED = 1, combination = (2 × 0) + 1 = 2. The pair reads 0 where the valve's position demands 2.
The result: combination 0 at a stop is missing feedback, so the InTransit text is a correct report of a lost closed signal, and the display needs no change.
The decision, by combination: 0 at rest means repair the feedback path; 3 at rest means repair the contradictory logic; 1 or 2 with the wrong text means repair the mapping in the project. For this case, walk the closed feedback in three steps. Check the input channel LED on the module with the valve held closed. If the LED is dark, the fault is field side: measure at the input terminal against the 24 V DC feed. A reading near 0 V DC at the terminal with 24 V DC on the feed side of the switch splits a failed switch contact from a broken wire; 24 V DC at the terminal with a dark LED points to a dead input channel. If the LED is lit while the tag still reads 0, the signal arrives and the project reads the wrong address, so the fix is the tag assignment.
Repair the signal, keep the text
- Both tags off at rest. Restore the missing feedback: failed switch contact, broken wire, blown fuse on the 24 V DC branch or a dead input channel, sorted by the LED and meter steps above. Nothing in the project changes.
- Both tags on at rest. Find what drives both state bits. Open the logic that writes the two tags: a rung that sets both, or two physical inputs wired from one device. Correct the logic or the wiring so one bit follows the open switch and the other follows the closed switch.
- One tag on, wrong text. Correct the assignment in the project: the open signal into the OPEN field, the closed signal into the CLOSED field, each text under its own state. Download the corrected project through your site's normal change procedure.
- Never force a state bit to clear the third text. A forced bit makes the screen claim a position the valve has not reached, and an operator breaking a line will act on it. Keep the InTransit text as it is; renaming it to something calmer changes the screen and leaves the signal fault untouched.
Confirm the repair on the live screen
- Valve held closed: OPEN reads 0, CLOSED reads 1, the closed text shows.
- Valve held open: OPEN reads 1, CLOSED reads 0, the open text shows.
- One full open-and-close cycle: the third text appears only mid-travel and clears at each stop.
- Remove any forces or test jumps used during diagnosis and watch one more cycle, about 60 seconds, with the logic clean.
Recommendation: read the OPEN and CLOSED tags live before you edit anything. When the pair reads equal at rest, repair the feedback or the logic at the source and leave the project alone; when the pair reads exactly one tag on while the wrong text shows, correct the tag assignment in the project and keep the third text unchanged. Renaming the InTransit label repairs nothing, and forcing a tag puts a false valve position in front of an operator.
Questions
My object words the third state differently. Is it the same fault?
Yes. The equal-inputs condition is worded InTransit on one object and in travel on another, and some packages let you edit the text. The condition behind the label is identical: the OPEN and CLOSED inputs read the same, so neither single end state is confirmed. Treat any wording of that third state the same way, by reading both tags live and sorting the case by the combination before you touch the text.
Can both state tags read on at the same time?
Not on a healthy valve with one limit switch at each end: fully open and fully closed are exclusive positions. Both tags on means the path is wrong somewhere: a limit switch contact stuck closed, two inputs fed from one device, or PLC logic that sets both state bits together. The object shows the same third text for both on and both off, so only reading the two tags live tells you which of the two faults you have.
Should I hide the third state so the screen always shows a position?
Keep it visible. The third text is the only display that says the feedback is missing or contradictory, and hiding it leaves a screen that always claims a confident position. If the wording worries operators, keep the meaning and fix the cause: once the open and closed signals read one on and one off at rest, the third text disappears on its own.
Planning information, not legal or engineering advice. Rules differ by place: check codes and permits with your local authority and your licensed trades.