Ygor0191

<snip>
I am not getting a 8180 Invalid port ID on the MB_COMMNDLOAD anymore. 

But my MASTER block is still given the 8180 error.

Do I need to add more to my code? 

</snip>

I am not particularly happy about the outputs of the FBs feeding back into its own DB. It would be best if those outputs receives it own memory / variables. Not too sure it will help you though.

Have you go through a STOP to RUN cycle to have MD_COMM_LOAD initiate the new configuration? Do consider putting an auxilary flag in to trigger the load function (in parallel) with the first scan bit.

Hi William_B

What do you mean by "Do consider putting an auxilary flag in to trigger the load function (in parallel) with the first scan bit."

Thank you

Ygor0191

Hi William_B

What do you mean by "Do consider putting an auxilary flag in to trigger the load function (in parallel) with the first scan bit."

Thank you

The coding that you shared only has the first scan bit connected to the loading function. My suggestion is to have another memory bit also connected. Sometimes you need to re-initialize the communication without forcing the PLC to STOP > RUN.

For example M999.7 is used in parallel with the first scan. Then when you download program changes and the communication does not work properly after that, you can trigger M999.7 from your PC to force an initialization.

#FirstScan
---|   |-------------|--->>
                     |
  %M999.7    %M999.7 |
---|   |------( R )--|

Hi William_B

Attached is the last version of my code. I followed your advice, but it did not work :(

I am a little frustrated, I know that the SEL 751A relay works via modbus because I tested it with modScan64 software on my computer. The comm load block runs with no error, but the Master block is still given me that 8081 invalid port id error. I made sure I inputted the correct slave ID, check the Rs232 cable, and to me my code made sense, I should be able to read.

One interesting finding is that the CM1241 rs2323 communication module on the PLC, Tx and Rx LED do not blink at all when I run the program. 

I have consulted with a professor at my university and he did not know how to help me.

thank you again for your support

Hope to hear from you soon.

Regards

Ygor

Do check your connections again.
RX to TX and TX to RX.

Now I have not used RS232 on the S7-1200.
Do review the x3 pins hidden from view on the MASTER instruction.
Those may be required to set for RS232.

At experts :- Please be so kind as to make yourselves heard.

Hi william_B

What do you mean by  "review x3 pins hidden from view on the MASTER instruction" 

I have look over the master block and Cant seem to find the hidden pins? Could you clarify this for me?

On another note:

I was looking into the S7-1200 manual the section 12.3.5.1 Configuring the communication module. In this example, an S7-1200 CPU communicates to a PC with a terminal emulator through a CM 1241 RS232 module. I have come to realize that I never did any configuration of the CM1241. All I did was detect the modules attached to the PLC, then look up the hardware ID for the module and make the COMM and MASTER blocks respectively.  

My question know is do I need to Program the PtP communications before using Modbus rtu communication? configure the PORT_CFG. SEND_CFG AND RCV_CFG blocks? because if so, that might be my issue. 

I have attached the section of the manual so you can refer to what I have said.

A thousand thanks for following up to my questions.

sorry for not being much help to you.
Yes a hardware configuration would be needed,
but the parameters seem the same as provided by ...

The 3 pins I spoke of earlier is FLOW_CTRL, RTS_ON_DLY and RTS_OFF_DLY. These are not hidden from view in the image above.

Something relating to the hardware seem to be the answer.. seeing that you do not get the TX and RX lamps flashing.

I hope you get this sorted.. good luck.
w

Ygor,

where are you sure that signal of MB_COMM_LOAD .. DONE was successful? PtP instructions are needed for simple PtP communication. Look, if you have success communication with PC program, what exactly COM settings you have on PC program side?

Update: simply go from that right situation that PC app work ok, so look at that communication settings and check on PLC same. But till this time I still don;t know about your .DONE status nothing.

Duris_I

Ygor,

where are you sure that signal of MB_COMM_LOAD .. DONE was successful? PtP instructions are needed for simple PtP communication. Look, if you have success communication with PC program, what exactly COM settings you have on PC program side?

Update: simply go from that right situation that PC app work ok, so look at that communication settings and check on PLC same. But till this time I still don;t know about your .DONE status nothing.

My friend Duris........ Thanks for helping.
Do know that Modbus RTU over RS232 is what is required.
The fact that the LEDs on the card does not flash is a clue.