Modicon Momentum and XMIT block...

[darrenj]

Hope every one had a good Christmas and isn't working to hard at the moment!!

I got a call from one of my customers and they asked if i would in interested doing the following job..

use a momentum PLC and RS232 to communicate with a Paging system. i said yes but as a learning exercise, so it means i am doing this on mostly my time (Mostly because they are going to pay what they budgeted).

So a couple of questions to start..(I haven't even seen the paging system or know what comms i am able to use..)but before i do here is a simple overview..

existing Modicon Quantum PLC system, 6 different processors covering approx 1500 Digital I/O and approx 100 analog I/O communicating with Modbus Plus also 8 or 9 Cutler hammer panelmates with the same comms. the new momentum processor will be dedicated to the paging system and is also on the modbus plus network. i was informed that they went with the momentum for the XMIT function that this unit has.. The processor will be "looking" at approx 260 points each point will page one of 5 groups and some will page individual pagers.

Now getting the alarms from the other PLC's is no problem for me, the problem is in using the XMIT block,so here goes...

1. am i better to program the processor with Modsoft or concept, If concept what language? Is the xmit function even available outside of 984LL?
2. how do i go about setting up the text to transmit to RS232
3. i can see messages getting bumped so i am thinking i will need some sort of FIFO thing going on and being deleted from the stack as the alarms are acknowledged..

anyone have some suggestions? My day tomorrow is spent in reading the paging manual and some limited info on the xmit..if you know of something else or an example i could expand on it would be much appreciated..

Thanks

Darren\

 

[darrenj]

some more info i found out today

the processor is a 171ccs70000 so i am stuck with ladder logic.
The info i have looked at for the XMIT block is starting to sink in, however while browsing in concept (Version 2.6 XL SR3) there are two ASCII formats one is ASCII the other is ASCII (4 Char)..How is it possible to store 4 char in the one register? If this is what i think it would be a major plus because most of the messages i will be sending are around 20-25 characters long plus the paging group info, so a total message length of 30 char. or so..thats 15 registers by 250 messages..thats 450 4xxxx registers..(I hope i am on the right track)

Comms with the paging system will be via RS232 direct, i first initiate the comms, send the paging group and then the message..

tomorrow i will try to create a simple message to send and then expand the logic from there..

on a side note i do find concept a little cumbersome with 984LL i am sure this is because i am not used to it, but it takes me twice the length of time to do anything with it than Modsoft..

 

[Jim Dungar]

984LL is an after thought language in Concept. I would not use it unless I was absolutely forced to, I prefer Function Block and resort to IEC ladder on those rare occassionwhere pure ladder logic is needed. If I am going to use 984LL I stay with ProWORX32.

XMIT is a 984LL command, for most of the rest of the Concept languages use XXMIT instead.

 

[darrenj]

Thanks Jim..any thoughts on the ascii vs ascii (4 Char)..?? if i get 4 in concept i will use it however if i can get the same thing with modsoft then i will stick with that..its what i know the best as well as the on site sparky..

 

[Jim Dungar]

Nothing wrong with Modsoft except its age. 984LL in Concept is basically the Modsoft command set without all of the good features.

I have no experience with ASCII (4 Char).

 

[darrenj]

I have no experience with ASCII (4 Char).

well that makes two of us then!!

any suggestions on the rest of the plan..i am a little worried about the amount of 4x registers..

the plan they have asked me to do is to use PLC21 to do all the alarming and store the messages..(Its a quantum 484 (??) series processor then basically as alarms come in move them to PLC15 (paging PLC)..i am not sure this will work as intended, unless there i use something other than Mbit to move the values...

mmmmm getting intersting...( for me anyway)

D

 

[Jim Dungar]

MBIT is for rearranging bits in a word. To move a block of words in one processor use BLKM. Or use the table commands, like T->R or T->T, if you want to do indirect moves.

XMIT is only used for making the PLC into a MODBUS master for serial communications. MODBUS PLUS does not use XMIT it uses MSTR instead, which allows both direct and indirect register moves between processors.

What is your PLC topography, all MB+?

 

[darrenj]

Yes its all MB+, You are right i am using the MSTR to move my bits between PLC's, Finaly got the XMIT to communicate with Hyperterminal today, Dosnt help that all the pin out diagrams were wrong, Finaly figured that out, the right pin out had the wrong PIN 1 point on the RJ45 diagram.

 

[darrenj]

one other thing jim..they want me to store the messages in another PLC and send them as required..can you send ASCII over Modbus plus?

If not then can they be sent by another method and converted??..this seems like a little two much..it would make more sense to store all the alarms in the pager PLC and just use the Bits from the other PLC's to send them..

D

 

[Jim Dungar]

Not really. Modbus Plus only sends 4x words.

But a word is nothing more than 16 consecutive bits, so MB+ does not know whether it is sending integers or ASCII characters.

 

[darrenj]

Played around with it again today..and figured i can do what they want..you are right MB+ just sends over whats in the registers, the XMIT block converts it to ASCII..

So i am going to use the MSTR To read say 30 contiguous registers and place them in the proper place for the XMIT function..and use the BLKM to move the registers in the first PLC for the MSTR to read..

while browsing in modsoft with the quantums i see a seperate section for ASCII..any ideas on if i can use this?

 

[Jim Dungar]

I have never worked with ASCII in 984LL. I have always used as seperate Quantum ASCII module. The old remote I/O interface modules often contained an ASCII port.