Micrologix reading data from SLC's and Control Logix Help

[cockrell960]

Hello,

I am currently trying to use a micrologix 1100 to read data from 7 SLC 5/05's and 3 Control Logix. I am only needing one word from each. They are all on the same network. Currently what i am doing is using the msg fuction in the 1100 and was curious if my configuration should work but i also want to prevent data collisions and network lag. They need to read every few seconds. My current configuration of the msg fuction for one slc is as follows.

Channel: 1 (integral)
500CPU Read
Data Table Address: N40:161
Elements: 1

Message Timeout: 23
Data Table Address: N10:1
Local
Multihop - Yes

MultiHop Tab:
Ip for SLC being Read

I don't know if this will work. I am also not sure how to not congest the network or what to use to limit continuous messaging every time the ladder is run.

I am also assuming i use the PLC5 Read to pull the data from the Control Logix since it uses Tag Names instead of data tables.

Any help would be greatly appreciated.
Thank You

 

[nightline]

In the ControlLogix PLC under Logic you'll find Map PLC5/SLC Messages...

 

[cockrell960]

I am not able to write from the control logix to the micrologix. i need to read the control logix from the micrologix. The reason for this is that the program is protected and was not written by my company. So i have no way to change the plc code to write to the micrologix which is why i will need to read from it instead. But thank you for your response

 

[Mike_RH]

You will have to change the program in the ControlLogix for the read / writes from the SLC/MicroLogix to work.

As Nightline said - you have to map the incoming SLC messages to/from an array tag in ControlLogix. The memory structure is different, the addresses have to be mapped.

 

[cockrell960]

Okay thank you. I guess i will try and get the company on the phone that wrote the program.

 

[cockrell960]

i have the ability to use a compact logix. should i use this instead of a micrologix to read the data.

 

[Mike_RH]

The CompactLogix can read the tags directly with a message. Do you know the tag names you wish to read in the ControlLogix?

 

[cockrell960]

I do have a list of tag names from the control logix plc that i need to read. Which is a DINT HMI_DISCRETE_ARRAY[27]. i am looking at performing the msg using cip data table read. im guessing this should work. Then for the SLC's using SLC Typed Read.
The communication path for the SLC would be 1,1,2,100.101.11.32,1,2 based on what i have read. Is that correct or am i getting confused on something?

I am also using a timer that counts to three seconds. When the counter hits 1 a couple of the msg block are run when 2 couple more when 3 a couple more. I am hoping this will limit the network congestion but also give a fast response time for the data i need. There is probably a better way to do it but as i said i am fairly new to messaging between plc's.

Thank you

 

[Firejo]

If you’re worried about network congestion then I would stagger your message instructions so only one is enabled at a time. If you’re able to wait three seconds to get all of your messages done then staggering shouldn’t be a problem time wise. I like the method where an integer is used as the regulator. For example, create “N10:0” and have the first message instruction enabled when “N10:0” equals “0” (using an “EQU”). When the first instruction goes either “done” or “error” you add “1” to “N10:0” making sure you’ve got a one shot on the rung so it only adds the “1” once. When “N10:0” equals “1” then the next message instruction is enabled again having the done or error bit add a “1” to “N10:0”. Of course the next message instruction would go enabled with “N10:0” equaling “2” and so on. When you reach the last message instruction, when it goes done or errors move a “0” into “N10:0” and the process will start all over. I learned this one from Ken Roach and it works well. There are other ways to do it but I’ve not had any problems with this method and I can even add logic to skip a message instruction if the need arises.