Newbie with a few questions

santisiah

Member
Join Date
Nov 2013
Location
Albuquerque
Posts
9
Hello all.. I am pretty new to programming PLC's and have a few questions. We are using Mitsubishi PLCs and HMI's and I am writing a new program. We have a lot of pumps and actuated valves we will be controlling so a lot of outputs. My question is, if we are using the internal relays in the program to control the 24VDC coils to the pumps, can I use M1 and continue with M's until whatever number I want or do I have to use the M's with Hexadecimal as I do with the outputs. These are only used for the push buttons on the HMI's and I don't have actual inputs from the "real world."

For example:

-||-, -||-, -||-, and so on..
M1 M2 M18

Hope you all understand what I am asking. Thanks for your help.
 
Hello all.. I am pretty new to programming PLC's and have a few questions. We are using Mitsubishi PLCs and HMI's and I am writing a new program. We have a lot of pumps and actuated valves we will be controlling so a lot of outputs. My question is, if we are using the internal relays in the program to control the 24VDC coils to the pumps, can I use M1 and continue with M's until whatever number I want or do I have to use the M's with Hexadecimal as I do with the outputs. These are only used for the push buttons on the HMI's and I don't have actual inputs from the "real world."

For example:

-||-, -||-, -||-, and so on..
M1 M2 M18

Hope you all understand what I am asking. Thanks for your help.

Hello,
The M bits are decimal. You start at M0 and go up from there. Keep in mind, some M bits are reserved for special functions depending on the PLC type. If you look in the help menu you should find a list of special relays/registers by PLC type.

Hope this helps,
Dave
 
...Can I use M1 and continue with M's until whatever number I want or do I have to use the M's with Hexadecimal as I do with the outputs.
The underlined phrase indicates that you think your "Y" outputs are Hexadecimal. They may be grouped in 16-bit words, but each Output is normally used as a single bit of a certain 16-bit word. That applies to "M" Marker bits also. Only at rare times will you need to treat Y outputs and M bits as a group (when you want to reset all bits in a word to 0, or write the same value (1 or 0) in all bits of a word).
 
The underlined phrase indicates that you think your "Y" outputs are Hexadecimal. They may be grouped in 16-bit words, but each Output is normally used as a single bit of a certain 16-bit word. That applies to "M" Marker bits also. Only at rare times will you need to treat Y outputs and M bits as a group (when you want to reset all bits in a word to 0, or write the same value (1 or 0) in all bits of a word).

Lancie, I think what he is talking about is the addressing structure when programming Mitsubishi controllers. The inputs and outputs are addressed in hexadecimal, i.e. X0-XF, Y0-YF. The internal M bits used like the B3:0/1 type in AB are addressed decimally. Data registers are also decimal.

This varies by PLC type, the Q series is as I described above, but the FX I/O is addressed in octal. The M bits and Data regs are always decimal though.

Dave
 
Thanks for clearing up that he meant the address numbering system. Many older PLCs used octal and hexadecimal address numbering due to the limits of the old hardware.
 

Similar Topics

Hello all, I'm a new member here. I've joined as I want to learn about PLC programming. I've got a few questions to begin with. To get me...
Replies
37
Views
4,429
Hello all Life long electrician, and been playing with a Mitsubishi FX3U-64M + FX3U-4LC PID controller. Its installed and programmed in a piece...
Replies
12
Views
4,504
howdy, taking my first dive into the world of RSSQL. Ive managed to open the app and view a list of transactions, but where can i go to actually...
Replies
3
Views
1,863
Howdy folks. Been doing PLC programming for like 15 years now in LD and ST, but I'm trying to learn SFC now and have a kind of dumb question... I...
Replies
4
Views
1,345
Hello. New to Unity and had a couple quick questions. Can a Modicon M340 output to a small multiline LCD screen and not a full HMI?
Replies
4
Views
940
Back
Top Bottom