Modicon 984 PLC & ADC EZ-Text Panel

bkf

Member
Join Date
Feb 2003
Posts
3
Does anyone know of a way to find out which memory locations correspond to a certain I/O address in Modicon's RLL?

I'm mating an Automation Direct EZ-Text 220P panel to a PC-E984-258 Modicon CPU setup. There's no problem setting up the WORD addresses for text entry. However, for the life of me, I can't figure out what bits to use for the buttons/leds/lamps. If I set them for WORDs 400200, 400210, 400220 (in the EZ-Text software), what on earth would I use for the BOOL input/output variables in the actual Modicon ladder?

I've done this with Automation Direct's DL-240 CPUs and it's easy to cross-reference the VMem WORD address with the internal contact relays, but I'm having no luck finding one with Modicon. Hopefully someone here is familiar with this setup?

Currently I've got the Panel configured to use 400100 for storage of 1 timer value, 400101 for the 2nd, etc... They're all called from within the ladder, directly inputting the 4xxxxx register location into the timer and work great.

But I'm stuck trying to figure out how to get the buttons/lamps/leds to work. :(
 
I received the following private email:


Hi Steve, just wanted to know if you could perhaps give me a little more info?

While I'm pretty confident in A-B and Automation Direct ladder, I must admit I'm a little confused by Modicon.

If I have the panel mapped to 400200 for the buttons (F1, F2, F3, F4, F5), how would I use this in the ladder? Obviously I can't use a BOOL function, since I can't call a WORD as a BOOL....

Do I have to use an FFB block to convert the WORD bit to a BOOL variable or something?

- brian


I guess the key question is the mapping of the function keys. If they're all mapped to register 400200, then presumably F1 is mapped to bit 00, F2 to bit 01, etc. In that case you'll need to be able to address a single bit of register 400200 or you need to copy register 400200 to something like 000200 so you can directly access the individual bits.

The other alternative would be to map F1 to 000200 or 100200, F2 to 000201 or 100201, etc. Note that the specific addresses are for illustrative purposes only.

I don't know enough about the details of either the EZ-Text panel or the 984 to advise you about which is the best approach.
 
Modicon Words and Bits

As Steve explained, the Modicon references usually associated with HMIs are: 4xxxx words (read/write, bits 1 to 16 left to right) and 0xxxx bits (read/write, coils). The usual preference is to have the HMI access the 0xxx coils rather than word bits.

Modicon's IEC language (Concept software) has Function Blocks (in the Extended library) for converting data types WORD_TO_BIT and BIT_TO_WORD.

Modicon's relay ladder logic language (984LL, ProWorx software) does not support the direct addressing of individual bits in a word, except in the Quantum PLC family. You can use the SENS command to examine the bits in a word and turn on corresponding 0xxx coils, however only one bit is examined per scan. I prefer to use a combination of logical XOR and OR commands. For example to transfer the bits from word 40200 to coils 00208 to 00224 - Use XOR command to reset all of the destination coils to 0, then use OR to have the coils mimic the word bit pattern, this all happens in one scan due to Modicon's scan method.


------- -------
-|00208| --|04200|
| | | |
|00208| |00208|
| | | |
| XOR | | OR |
| 1 | | 1 |
------- -------

 
Not sure I'm understanding. :( I'm writing in the LD editor inside Concept 2.5.

The panel button function can be assigned a single WORD address, and then uses bit registers for each button.

Unfortunately, I'm not sure what WORD address I should be using. Once I DO have a WORD address (4xx or 3xx?), how do I access the bit registers using Modicon's LD editor?

In Automation Direct's DirectLogic32, the V-Mem locations are cross-referenced already. If I set a WORD address of V40605, I'd just use the internal contact relays of (hypothetically) C40, C41, C42, etc... for the buttons. I don't have to do any conversion rungs.

Since I'm not familiar with Modicon's method of accessing the registers, I'm a bit stumped. The panel can only put out 16-bit WORD format, so unfortunately I have not way of accessing coils directly.

Currently I do have timer values stored in the PLC under 400200-400210, and have the panel pointing to those addresses with Text-entry and that works great. I change the timers with the numerical panel and they're updated and used in the ladder.

It's the bit registers that I'm completely lost on.
 
This is an issue with how your HMI handles Modbus commands, not with the way Modicon does it.

With Concept 2.5 IEC ladder logic, you should use the WORD_TO_BIT function found in the FFB Extended libary, under conversion.

This function will accept a word (i.e. 40300) from your HMI as the input and then output 16 consecutive coils. The coils can be used in your program as located variables (i.e. 0208 to 0224) or as unlocated variables. These variables can then be used in your ladder program as any other coil/contact. The corresponding output conversion would be BIT_TO_WORD.



|-----------|
|WORD_TO_BIT|
------|EN En0|-
| |
40300-|In Bit 0|-()
| Bit 1|-()
| Bit 2|-()
| Bit 3|-
| Bit 4|-
| Bit 5|-
| Bit 6|-
| Bit 7|-
| Bit 8|-
| Bit 9|-
| Bit 10|-
| Bit 11|-
| Bit 12|-
| Bit 13|-
| Bit 14|-
| Bit 15|-
|-----------|


 
Thanks, Jim! The WORD_TO_BIT FFB was the missing unknown. Dropped that in, set my variables, and now the panel buttons work just fine!

Thanks again!
 
Current Modicon offering

Allen,

Modicon offers IEC programming languages (using Concept software) on all of it's current families. Momentum processors need to be ordered as either IEC or 984LL. The new generation of Compact units with 386 processors and all of the Quantum family are either/or.

The older generation of processors were only ladder logic.

The confusion comes from the fact that there was a family of 984 processors as well as the programming language of the 984 Ladder Logic instruction set.
 

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