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ST1004 Sequence Controller


A. General Description

The ST1004 Sequence Controller is a programmable timer which allows the user to sequentially turn on up to six 24VAC outputs one after another. Originally designed to sequentially control solenoid valves in fluid pumping systems, it can be used in any application where similar functionality is required. It operates on 12 VAC or Industrial Standard 24VAC. A 24 VAC transformer is supplied.

The ON TIME of the outputs are set by a front panel control which allows the time to be adjusted from 0 to 10 minutes. After each CYCLE, where all the selected outputs have been sequenced on in turn, the unit allows the setting of a RECYCLE DELAY from 0 to 50 minutes before another CYCLE, or on sequence of outputs is started.

The NIGHT MODE function will enable the unit to inject a 0 to 4 hour NIGHT MODE OFF TIME after each cycle instead of the RECYCLE DELAY. This is enabled when turned on and when ambient light disappears. Another useful feature in NIGHT MODE is the capability to have a 1 minute SHORT CYCLE sequence injected between the NIGHT MODE OFF TIME and the normal ON TIME cycle set by the front panel control. This allows each output to be turned on for 1 minute only for one complete cycle before the normal ONTIME cycle.

Whenever the NIGHT MODE OFF TIME is active, NIGHT MODE OUTPUT is turned on.

An AUXILIARY output is another useful feature of the ST1004. This is a common output which the user can elect to turn on whenever any output is on. An example would be where the sequenced outputs are turning on fluid valves, the AUX output would drive the pump, which must be on whenever a valve is turned on, and off whenever no valve is selected.

B. Installation

Attach the unit to the desired location with the key type mounting hole in the side flanges of the case.

All the terminal blocks supplied with the unit are screw type for easy attachment, and unpluggable so that the unit can be removed from the system if desired without disconnecting any wires. When plugging these in, all plugs insert with the wire clamping screw facing away from you, towards the back.

Power is supplied to the ST1004 from the supplied Class 2 transformer. This supplies power to the units control processor, as well as to all the attached loads.

Attach the two ring terminals on the power cord to the transformer screws on the back of the transformer. Insert the plug end of the cord into the 3 pin connector located on the left side of the bottom face of the unit.

Loads are attached to the unit with the 2 pin connectors on the bottom face of the unit. The ST1004 supplies 24VAC power to all the load output connectors.


Loads are limited to those which require 24VAC with a current draw of no more than 0.8 amps. This is equivalent to 20 watts. These can be resistive or inductive loads. To drive larger loads it will be necessary to use a suitable interface device such as a contactor, or for increased reliability, a solid state interface such as the HGS Engineering D1005 1Hp 15 Amp Solid State Drive.

The ST1004 will operate on 12VAC, however, since the unit supplies the drive voltage to the loads, they must also be 12VAC.

C. What are Time States

Time and Time States

The ST1004 is a sequence timer. This means that it is a timer which turns on from 1 to 6 outputs, not all at once, but in a time sequence, one after another. These Time Sequences are called TIME STATES. It is important to start thinking of the operation of the ST1004 not in terms of outputs, but of TIME STATES which have a dedicated output associated with each Time State.

Each Time State is length of time set by the front panel TIME STATE ON TIME. These represent sequential periods of time. Things we do everyday which are sequential, can be viewed this way, as individual time states where some activity happens. We may even have a time state where we do nothing more than wait a period of time for something else to happen.

The top set of switches of the ST1004 are the TIME STATE ENABLE switches. When up, ON, that time state will be entered when it is its turn. When the switch is down, OFF, it will be skipped over. The ST1004 will display which Time State it is in by turning ON the indicator light directly below the Time States enable switch. One sequence, starting with the first Enabled time state and finishing with the last Enabled time state is called a CYCLE.

If all Time State Enables were to be put in the ON position, each indicator would come on in sequence, starting at Time State 1, for a period of time set by the TIME STATE ON TIME control, and ending with Time State 6. If any of the Time States are disabled, they will be skipped over. The total time for one CYCLE is equal to the ON TIME times the number of Time States which are enabled.

Time State Outputs

Each Time State has an output associated with it. This output would be connected to any device that you wished to control during that Time States period of time. Its output can be turned on or off separately with the bottom set of switches labeled OUTPUT. If in the up, ON position, that output will come on whenever its Time State indicator is on. If in the down, OFF position, that output will remain off, however, the time state will still remain on for the ON TIME period. This is where it is important to think in terms of Time States because the ST1004 may be in Time State 4 for example, but its output will not come on because its output switch is OFF. This may be useful when you want to wait for a period of time between events, or when servicing equipment where the output has to be off, but the Time State time still has to be there to maintain the overall cycle time period.

Time State Auxiliary Output

Also associated with each Time State is an Auxiliary output. This is a single output which would be connected to a device common to all Time States. Each Time State wishing to control this device during its period of time would have its Auxiliary switch in the up ON position. This would for example control a pump. If the ST1004 were controlling fluid solenoid valves, whenever any Time State output turned its valve on , the Auxiliary output to the pump for those Time States would also be turned on if their Auxiliary switches were turned ON.

D. Operational Overview

Figure 1 illustrates the sequence of events that happen in the operation of the ST1004. When first turned on, the unit looks for the first TIME STATE which is enabled. If no TIME STATE is enabled it will wait until one is. When seeing the first, the unit will turn on for the period of time set by the ONTIME control on the front panel. When finished it will look for the next one enabled, skipping over any TIME STATES which are not. It will continue until the last enabled TIME STATE of the 6 has been turned on. This is one complete sequence CYCLE.

image Place Holder

Upon completion of the first cycle the unit has two choices depending on the setting on the front panel. It can enter a RECYCLE DELAY, settable from the front panel for up to 50 minutes, or it can enter a NIGHTMODE OFFTIME DELAY, settable for up to 4 hours.

If the NIGHTMODE condition is met, the ST1004 will enter NIGHTMODE, if not the unit will enter RECYLCE DELAY mode. NIGHTMODE condition is met if the NIGHTMODE switch is ON, and if ambient light drops below a preset level indicating a night condition exists.

The function of this feature would be in a garden system where the ST1004 is controlling the pumping of solution to a number of different gardens. Normally the ST1004 would turn a valve on to each garden in sequence, then wait the RECYCLE DELAY, eg 50 minutes, before doing it again. Since nutrients are not taken up as fast in darkened conditions, when night falls, the unit would enter the NIGHTMODE delay of up to 4 hours, decreasing the frequency of feeding.

When the unit has just finished a NIGHTMODE DELAY, the gardens may have been without nutrient for up to 4 hours. Normally, if there are 6 gardens running with the full 10 minute ONTIMES, one cycle will be 10 min. times 6, or 60 minutes. If NIGHTMODE is set for 4 hours, the last garden will not get nutrient for 4 hours plus 5 ONTIMES, or 4 hours in dark, 50 minutes in light.

To remedy this, the ST1004 has a special SHORT CYCLE mode. After exiting the NIGHTMODE OFFTIME DELAY, the cycle will start again but each TIME STATE will come on for only 1 minute each. See Figure 2. After this is completed the unit will start another cycle with no delays but with the normal ONTIME taken from the ONTIME control setting. The SHORT CYCLE switch must be ON for this feature otherwise the unit will do one normal ONTIME cycle only.

This allows each garden to get a quick 1 minute feed of nutrient to hold it over before the normal ONTIME cycle is started.

E. Operational Controls

1. TIME STATE ENABLE switches - turns on an individual time state. A time state must be enabled before its output or auxiliary switches will function. Once enabled, both output and auxiliary switches for that time state are functional independently.
2. TIME STATE OUTPUT switches - one switch per Time State. Allows that time states output to be ON or OFF when that time state is on.
3. AUXILIARY OUTPUT switches - one switch per Time State. Allows the common AUX output to be ON or OFF when that time state is on.
4. ON TIME control - Sets the time the ST1004 will turn on each time state. Adjustable from 5 seconds to 10 minutes.
5. RECYCLE DELAY control - Sets the time the ST1004 will wait between completed ONTIME Cycles. Adjustable from 23 seconds to 50 minutes.
6. NIGHTMODE OFF TIME - Sets the time the ST1004 will wait in NIGHTMODE before starting another ONTIME Cycle. Adjustable from 2 minutes to 4 hours.
7. NIGHTMODE Switch - Enable or disables NIGHTMODE. This switch must be ON and ambient light must disappear before a NIGHTMODE OFF TIME will be injected between ON TIME Cycles.
8. SHORT CYLCE Switch - Enables or disables the one minute ON TIME Cycle immediately following a NIGHTMODE OFF TIME.
9. NIGHTMODE ACTIVE Indicator - indicator lights whenever the ST1004 is in the NIGHTMODE OFFTIME DELAY mode waiting to start another Cycle. This indicator also indicates when the NIGHTMODE Output is ON.
10. RECYCLE DELAY ACTIVE Indicator - indicator lights whenever the ST1004 is in the RECYCLE DELAY mode waiting to start another Cycle.
11. AUXILIARY OUTPUT Indicator - Indicator lights whenever the AUXILIARY Output is
ON. This indicator will be ON when any enabled TIME STATE is on and its AUX OUTPUT switch is turned on.

F. Typical System

To best illustrate the operation of the ST1004 Sequence Controller, an example of an application system is shown in Figure 3.

In this system, four separate gardens are being controlled. Each garden is connected to the pumping system by an electrically operated solenoid valve which allows nutrient to flow to the garden only when a voltage is applied to it. Outputs 1 to 4 of the ST1004 are connected to the valves for gardens 1 to 4. A fifth valve will be described later.

The Auxiliary output is connected through a D1005 Solid State Drive to control the pump motor. This is a plug in unit. The D1005 is required because the ST1004 cannot directly supply the power required by the pump motor.

If your system is operating with a CO2 injection system, the Night Mode output can be use to shut down the CO2 whenever the ST1004 is in night mode. This output can be used for any device you wish to control whenever no light is present in the garden area.

The ST1004 would be setup in the following manner

TIME STATE enables 1 to 4 ON, 5 and 6 OFF
TIME STATE outputs 1 to 4 ON, 5 and 6 OFF
AUXILIARY output 1 to 4 ON, 5 and 6 OFF

With these settings the ST1004 will sequentially turn on gardens 1 to 4 for the time set by the ON TIME control then wait for a time set by the OFF TIME control before starting again. TIME STATES 5 and 6 will be skipped.

The order in which each garden is connected, whether they are one after another, or with TIME STATES between them is your choice. For example, it may be better for your system to have a time delay between the watering of gardens 1 and 2, and gardens 3 and 4. The system could be rearranged to have gardens 1 and 2 on TIME STATES 1 and 2, gardens 3 and 4 on TIME STATES 4 and 5. Set the ST1004 as follows.

TIME STATE enables 1 to 5ON, 6 OFF
TIME STATE outputs 1and 2 ON, 3 OFF, 4 and 5 ON, 6 OFF
AUXILIARY output 1 and 2 ON, 3 OFF, 4 and ON, 6 OFF

With the ON TIME set for 5 minutes, this configuration would cause gardens 1 and 2 to go on for 5 minutes each, then a 5 minute wait when nothing happens, then gardens 3 and 4 to go on for 5 minutes each, then start the RECYCLE delay.

This system allows the user to configure the system to their best advantage.

In the example shown in Figure 3, output 6 is connected to the pump out solenoid valve. When it is desired to pump the system out, turn on all switches for output 6. When the ST1004 finishes the last garden, it will then start a pump out sequence. It may be required to have safe guards on a feature like this to prevent accidental pump out, or to prevent the pump from running dry if all nutrient is pumped out before the ST1004 has finished the TIME STATE. Manually turning the pump on when finished with the TIME STATE output switch will prevent the latter condition.

Keep in mind when designing your system that the TIME STATE outputs can be used to control any system equipment that you would wish to control in the sequence. This can even be the sequential control of equipment relating to a single garden.

Plan your system out carefully before starting construction to ensure you get the maximum capability from your garden system. It is much easier and cheaper to make corrections on paper than to have to do wiring and plumbing hardware changes later.

G. Electrical Specifications

Input Power - 9 to 24 VAC
-1.6 amps maximum

Outputs - 9 to 24 VAC
- 0.8 amps, 20 watt maximum

H. Timing Specifications

Time State On Time -5 seconds to 10 minutes

Recycle Delay - 23 seconds to 50 minutes

Night Mode Off Time - 2 minutes to 4 hours

Short Cycle On Time - 1 minute

I. Physical

Size - 2in. x 6in. x 12in.

For more information, please visit this products webpage.
This product was added to our catalog on Tuesday 16 September, 2003.
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