Internet PLC Forum

Gary I really appreciate the quick turn around for your response on this subject.
I created a Custom Function (FIFO) that is called from the rising edge of relay 146
So when a message is created and stored into A$ the relay 146 is turned on
I then inserted your sample program into the Custom Function & removed your Call DequeueMsg
I then included #   #Define Name   Value
1   ENQ_Offset      DM[1700] // DM1700 to DM1800 not used anywhere else
2   DEQ_Offset      DM[1701]
3   FIFO_Cnt         DM[1702]
4   FIFO_Size         15
5   FIFO_StartAddr   10

Also I changed your B$ to E$ as I was already using B$
When I run the simulator and Type in a message into A$ then I trigger Relay 147 nothing happens
I tried it many times and the value in FIFO_Cnt never changes
I see you use an Old Version of software and use ' for Rem Statements I found using the // makes the program easier to read. Can you please look over the program below & let me know where I went wrong.
Also when it is working how can I read the Stored Messages?

Actual program
// This function is used to store the latest 15 Fault Messages the the PLC has detected.
// This Custom Function was created with the expert help from GARRY DICKINSON

// EnqueueMsg - function to enqueue an array of 40 character messages into the Message FIFO

// On entry A$ holds the string to enqueue
// This FIFO uses the SAVE_EEP$ statement to store data in the non-volatile memory.
// The message length is limited to 40 characters

// On exit: The A$ will be written to the FIFO
//         The FIFO_FULL and FIFO_EMPTY RELAYS may be affected.
//        The DM[] variables ENQ_Offset, DEQ_Offset and FIFO_CNT may be updated.
//         If the FIFO is full then the E$ variable will be written with
//           the oldest message in the FIFO to make room for the new message


//  If the FIFO is FULL, then discard oldest message in the FIFO

IF TestIO(MsgFifoFull) // the FIFO is full so we will discard the oldest to make room for the newest message.
                     // This action will overwrite the value of E$
   
ENDIF

SAVE_EEP$ A$,FIFO_StartAddr + ENQ_Offset   // Write one entry into the FIFO      

                                 // Update the FIFO index, counter and flags

ENQ_Offset = (ENQ_Offset + 1) MOD FIFO_Size
FIFO_Cnt = FIFO_Cnt + 1

IF FIFO_Cnt = FIFO_Size
   SetIO MsgFifoFull         // the FIFO is full and cannot accept more data
ENDIF

ClrIO MsgFifoEmpty           // FIFO cannot be empty


// This is the entire custom function to enqueue a string in the FIFO:
// Code:

// DequeueMsg - function to dequeue String data from the String FIFO

// On exit:  E$ will hold the oldest string in the FIFO.
//        The FIFO_FULL and FIFO_EMPTY RELAYS may be affected.
//        The DM[] variables ENQ_Offset, DEQ_Offset and FIFO_CNT may be updated.


// Return message from FIFO in E$
 
IF TestIO(MsgFifoEmpty)
   // the FIFO is empty and there were no values to remove from the FIFO
   // Just return a NULL String
   //
   E$ = ""
ELSE
   // the FIFO was not empty, so return oldest message in E$]
   
   E$ = LOAD_EEP$(FIFO_StartAddr + DEQ_Offset)

   // Update index, FIFO count and flags
   
   DEQ_Offset = (DEQ_Offset + 1) MOD FIFO_Size
   FIFO_Cnt = FIFO_Cnt - 1

   IF FIFO_Cnt = 0
      SetIO MsgFifoEmpty   // the FIFO is empty and there is no more data to remove
   ENDIF

   ClrIO MsgFifoFull        // FIFO cannot be full
ENDIF

Gary somehow I knew it would be you that answered the question.
I totally understand the concept of a FIFO First in First Out. I don't care if the oldest message gets lost.
The easiest way to explain what I need to do is this. Even though I am using a Text display I cannot use the built in Alarm function as the text display is not normally connected to the plc. it is only connected when the mechanic comes along for service or to repair a shut down then when they are finished they take the display with them as it is used as a tool.
What I need to accomplish is a way of storing say up to 15 (up to 20 Character Long Messages) that can be retrieved either by logging into the PLC and viewing them or by retrieving them and viewing them on the text display.
I can create multiple screens in the text display that will show the messages in order. Or I can use one screen and increment or decrement a counter to move the various messages into the same variable message.
The message to be moved into the FIFO will be A$
However I have the problem of that I have already used up most of the Variable strings A$ to K$ as well as W$ to Z$ so I actually don't have 15 spare variable strings.

Regards
Lorne

This issue seems to be resolved.
I deleted the screen that was using the 2 buttons pressed then made a new screen from scratch and now it seems to work properly. Both buttons need to be pressed then released and the released task works. If only one of the buttons is pressed then released nothing happens which is the way it is supposed to work.

I am concidering this as a bug due to the actions of the properties.
When you chose two buttons together to cause an action during buttons pressed every thing works perfect.
However under released tasks it only looks at either of the buttons not both.
Example 2 buttons pressed F1 & F4 set bit
Press just F1 or F2 nothing happens however when you press and release either F1 or F2 and release the task set in released takes effect.

Once you figure out the difference between the FP4030MR and the TRI-PLC everything works smoothly.
One small quirk you may or may not run into is that if you use lots of screens like I do you will need to separate the screens that the PLC calls and the screens that the Text display calls.
Not everyone uses text display the way I do so I will try to explain it in simple terms.
Because we do not permanently attach the text displays to the finished product but use it as a tool for our dealers to be able to adjust parameters that we allow the to adjust as well as use it for trouble shooting purposes. I therefore cannot use the standard Alarms so when ever the test display is plugged in and an alarm occurs the plc switches the screen to our alarm message page. To do this you need to move the value of the screen into the screen trigger register of the text display. Also I have it set up so that when you press two buttons at the same time the screen will switch to our start of the setting screens. To do this I set a bit in the PLC when ever the buttons are pressed to block out the PLC from changing the value in the screen trigger register and now the individual screens change the screen trigger register.
Then at any time someone presses the ESC key I reset the bit that was original set and the screen switches back to the main screen then resets the ESC bit.
Other than the original addressing quirks I mentioned I found the FP4030MR very easy to work with and it has a lot of good features.
If you have any other questions regard the FP4030MR let me know and hopefully I can answer them. After all old guys have to help each other out

Gary I was very impressed with your replay.
What I was doing was dividing the PLC address by 8 then I would at least get the main addressing of the relay inside the FP4030MR but I was always off by 1.
After I read your response it finally hit me that the text display starts at 0 and the PLC starts at 1.
I was very surprised that the TRIPLC starts at address 1.1
When I first started learning the ins and outs of the TriPLC I struggled with the fact that all their addressing starts at 1 and not 0 like most other manufactures DM0, Input 0.0, Output 0.0
 

I am still confused about the correct addressing inside the MD4030 MR when it comes to internal relays and input and output on the FX2424
Whit some trial and error I found that RC00059.00 actually turns on Relay 473, RC00059.01 turns on Relay 474 and so on.
Is there a simple formula that I can use to figure out a faster way to get the address correct?
Example what would be the correct IC number in the FP403MR to turn on Input 17 on the PLC?
What formula to use to figure out what RC number to trigger say Relay 146 inside the PLC?

I was looking over questions posted in the Forum and came across this post.
As a long time PLC user I found that it was a little frustrating that the Define Table did not have a column to allow for a description as most PLC software always allows for a description in their Symbolic File.
This would be a great feature for TriPlc to add to their software.
In the mean time I exported the file into Excel and made a column where I added the descriptions and keep the printout close by when working on the program.