AB SLC500 Help needed with sequencer Pls.

Hi Guys,
I am still waiting to get on an AB programming course but have a project to complete before its possible.

If someone could help me i would be most gratefull, I would be happy to send you coffee and doughnuts <smile>

This project is starting to do my head in, it is to empty 8 silo's in sequence, only one emptying at any one time, there are 2 banks of 4 silo's, there is one motorised valve on each silo and one for each line from each bank of 4 silo's making 10 valves in total. there is also RTD sensors fitted to each bank discharge line and one for the fill line (3 RTD's in total) the contents in the silo's is a mixture of liquid and solids.
I need to provide lights to show valve closed or open (20 lights) Light for running and light for fault. 1 switch to run the sequence, one push button to clear fault, one push button to advance step.

The processor will be the 5/03 in the 7 slot rack
1 RTD input card
2x 16w digital input cards
2x 16w digital output card

Valves would be positioned as follows:
S= Silo, Main line from bank=M, V= Valve

Bank 1, SV1, SV3, SV5, SV7, MV9
Bank 2, SV2, SV4, SV6, SV8, MV10

Valve MV9 would only open if SV1,3,5 or 7 opens
Valve MV10 would only open if SV2,4,6 or 8 opens

Valves are energise to open and spring return to close.

The sequence of valve operation would be SV1, 2, 3, 4, 5, 6, 7, 8, 1, 2, etc. no stops, continous cycles.

Temperature measurement via RTD as follows:

Inlet temperature = T1
Outlet temperature bank 1 = T2
Outlet temperature bank 2 = T3

There will be 2 feedback switches fitted to each valve giving indication of open and closed position, configuration can be NO or NC as they are a common V3 microswitch.

What i need to achieve is the following:

One input (2 pos) switch to enable

When things are working correctly then:

If switch contact is closed to enable sequence (run) then, open any valve, check for differential lessthan/= to 4c, if so then step to next valve in sequence. If differential lessthan/= to 4c is not achieved within 20mins then step to next sequence.
8 lights would be showing 8 valves are closed and 2 lights would be showing 2 valves open.

When things go wrong:
IF valve sticks in closed position, flash that valve closed light. trigger a move to the next step/valve
IF valve sticks in open position, flash that valve open light. time for only 5 minutes on faulty valve then move to next step/valve.
If valve sticks midway show fault light (or flash both open and closed lights) time for only 5 minutes on faulty valve then move to next step/valve.

Reset button to reset only flashing/fault lights.

Any assistance would be most gratefully welcomed, i would even be prepared to make a donation to anyone wishing to write the code for me.

Thanks to all for reading and hope you can help me with this problem.

Regards Chris

chrisflint said:

Hi Guys,
I am still waiting to get on an AB programming course but have a project to complete before its possible.

Any assistance would be most gratefully welcomed, i would even be prepared to make a donation to anyone wishing to write the code for me.
Regards Chris

Click to expand...

Chris:
I'm in a couple of projects right now but your offer for donation is a temptation.
Anyway this is how i'm gonna try to help you.
To make things easier try using valve states like this:
LS1 is activated when valve is closed, and LS2 is activated when valve is open, SV is solenoid or motorized valve.
State 0 means valve is close, that means SV is zero, LS1 is 1 and LS2 is zero. RED light is on. Move zero to state.
State 1 means valve is open, tht menas SV is 1, LS1 is zero and LS2 is 1. Green light is on. Move 1 to state.
State 2 is problem to close, sv is zero, but LS1 is not zero, red ligh is blinking. Move 2 to state.
State 3 is problem to open, SV is 1, but LS2 is not 1, green light is blinking. Move 3 to state.
Using states saves you a lot of space, because you use state and forget about LS and solenoids. You can use a timer to wait for the valve to operate, so you do not have false states.
You can also use another state called machine state to know where you process is located, that is what valve is operating and what is the next one, so when something goes wrong and you depress next state button you know where to go.
Use a subroutine only for valve state, use one for machine state, use one for alarms, etc.

Chris,

1. Make a list of all Outputs, 32 in all: SV1, SV2,...,SV8, MV9, MV10, RUN, FAULT, SV1 OPEN, SV1 CLOSED, ..., MV10 OPEN, MV10 CLOSED.

2. Decide how you will arrange the SV (Solenoid Valve) Outputs so that you can easily operate them with a Sequencer (SQO) instruction. I suggest installing all 10 solenoid outputs on the same digital output module, SV1 on Output 0, SV2 on Output 1, and so on up to SV8 = Output 7, MV9 = Output 8, MV10 = Output 9. The remaining 6 outputs on that module and 16 on the second module can then be used for the 20 open and closed valve position indicating lights, the Run Light, and the Fault Light. Now assign modules to slots, and assign outputs to module terminals.

3. Make a list of all Inputs.
Digital Inputs, 23 in all:
RUN/STOP Switch (1 = Run, 0 = Stop)
Manual Step Advance Pushbutton (assuming that sequence is normally automatic)
Fault Reset Pushbutton
SV1 Open, SV1 Closed,...SV8 Open, SV8 Closed,
MV9 Open, MV9 Closed, MV10 Open, MV10 Closed
Assign Input modules to slots, and assign inputs to module terminals.

Analog Inputs, 3 in all:
Inlet Temperature T1
Bank 1 Outlet Temp T2
Bank 2 Outlet Temp T3
Assign the RTD module to a slot, and assign the 3 temperatures to RTD module terminals.

4. Answer Questions:
Is it a requirement that MV9 and MV10 be operated by the Sequencer? It will simplify your logic if MV9 and MV10 can be operated by OTE's (other than a sequencer instruction). If it is an unstated requirement that MV9 and MV10 be operated by a sequencer, then put these on a separate sequencer that only has two steps: MV9 Open, MV10 Open.

Is the "one push button to advance step" a Manual Advance button? I assume from the description that, once started, the sequence is continuous unless a fault occurs. Is the "advance step" pushbutton therefore a Manual Step Advance pusbutton?

If differential less than/= to 4c is not achieved within 20 mins then step to next sequence.

Click to expand...

Differential in what? Temperature in degrees C? Usually when emptying silos, you would look at a Low Level switch to determine when it is empty. Please explain what "4c" means. If it is a difference in temperature, then which temperatures? Between Inlet and Outlet temperatures? If it is temperature difference, then this is more of a Batch Mixing Process, based on temperature, rather than a Silo Emptying operation.

5. Decide what inputs are needed, and how to arrange them, and what other instructions are needed, to make each Ouput operate as instructed.

Send me a message if you need more help.
Regards, Lancie