SQL — Sequencer Load

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Description

SQL (Sequencer Load) fills a sequencer table from live values, one step per rung edge. Each time its rung goes from false to true it advances the position and copies Source into the array element at that position. Use SQL to teach a machine: run a good cycle by hand, advance the SQL at each step, and the table that an SQO or SQC will use is recorded without typing it. Do not confuse the mnemonic with a database query; here it means Load.

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Operands

Operand	Type	Format	Valid Range	Required	Description
Control	CONTROL tag	Tag or Tag[n]	One SQL per control tag	Yes	Holds LEN, POS and the status bits.
File	INT or DINT array tag	Tag	At least Length + 1 elements	Yes	The table being recorded; element 0 is the parked position and is never written.
Source	INT or DINT tag, member, element or literal	Tag, 25	Any	Yes	The value recorded at each step.
Length	Whole number	4	1 to array size − 1	Yes	Number of steps.
Position	Whole number	0	0 to Length	No	Starting position at power-up.

There is no mask; the whole Source word is stored.

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Scan Behavior

Prescan

LEN is loaded from Length and POS from Position. The table is not written.

Rung-condition-in is false

EN is cleared. Nothing advances.

Rung-condition-in is true

On the scan the rung turns true, POS advances by one, wrapping from Length to 1, and Source is written to File[POS]. DN is set while POS equals Length.

Postscan

Nothing.

Condition	EN	DN	POS	File
Power-up	0	0	Position (usually 0)	holds
Rung false	0	holds	holds	holds
False → true	1	POS = LEN	+1, wrapping LEN → 1	File[POS] = Source
Held true	1	holds	holds	holds
RES on the control	0	0	0	holds

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Member Bits

Bit	Mnemonic	Data type	Set by	Cleared by	Operation description
Enable	.EN	BOOL	The rung being true	The rung being false, or RES	Mirrors the rung condition.
Enable unload	.EU	BOOL	Never	RES	Reserved.
Done	.DN	BOOL	POS reaching LEN	The next advance, or RES	The last step has been recorded.
Empty	.EM	BOOL	Never	RES	Not used by SQL.
Error	.ER	BOOL	Never	RES	Reserved. Bad operands are refused at validation.
Unload	.UL	BOOL	Never	RES	Not used by SQL.
Inhibit	.IN	BOOL	Never	RES	Reserved.
Found	.FD	BOOL	Never	RES	Not used by SQL.
Length	.LEN	INT	Length at power-up	Never (RES preserves it)	Number of steps.
Position	.POS	INT	Each advance	RES (to 0)	The step just recorded.

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Example

Scenario: A setter walks a new product through the four stations and records the required dwell at each one. The value typed into Teach_Val is captured into the table at each teach button press.

Tags:

• Seq_Teach — Teach button, BOOL
• Learned — Recorded table, INT[5]
• Teach_Val — Value to record, INT
• SQL_Ctl — Control, CONTROL, Length 4

Rung 1:

—] [Seq_Teach———[SQL SQL_Ctl  Learned  Teach_Val  4]———

Scan 1 — Seq_Teach = 0. Teach_Val reads 25. Position 0, the table untouched. The SQO and SQC rungs above are their own pages’ examples.

Scan 2 — Seq_Teach = 1. Position advances to 1 and Learned[1] becomes 25. The File list under the operand is trimmed in the middle, so the 25 shows as 2…; the Tag Browser shows the full element.

Change Teach_Val and press again for steps 2, 3 and 4; DN lights on the fourth. The table is then ready for an SQO with the same Length.

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Control Tag Errors and Troubleshooting

Error definitions

.ER cause	Condition that sets it	.POS / status value	Meaning
None	.ER is never set by LadderIDE	—	A File that is not an INT/DINT array, or a Length of array size or more, is refused at validation.

Troubleshooting hints

Symptom: Element 0 of the table never changes. Likely cause: Position 0 is the parked position; the first advance writes element 1. Fix: That is intended. Leave element 0 as a placeholder.

Symptom: The recorded values are one step off. Likely cause: The teach press happened before the value was updated on the same scan. Fix: Update Source on the scan before the teach rung, or drive the SQL from the value-change itself.

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See Also

• SQO — Sequencer Output (play the table back)
• SQC — Sequencer Compare (check against the table)
• COP — Copy File (copy a taught table into a recipe array)
• Shift/Sequencer Instructions — Category index

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Notes

Retention. The table lives in an ordinary array tag, so it survives only as long as the controller is powered unless the project stores it as the tag’s literal.

The block colours neutral. Watch the rung wire, the Position row and DN.