A2NCPU cannot communicate to PC

Hello! I have a problem with our A2NCPU it does not communicate to PC anymore, when I about to upload the medoc program by using SC-05 cable RS422, it says that "no reply from PLC-system", I'm just wondering why the plc port cannot communicate anymore? is there a way to repair the communication port of A2NCPU? I'm pressumed that when I connected the MAC50 display to the PLC,it caused the damaged of the PLC's port, assuming the communication is damaged already, is there anyway to repair it? what is the alternative solution for this? in order to load the medoc program project? please help me. your response is higly appreciated. thank you.

I am not sure what an SC-05 is. This might be a Mac programming cable. The cable you need for the A2N should be an SC-02(very old), SC-03 or SC-09.
Andybr

Hi Andybr! SC-05, SC-08 & SC-02N are the converter unit for connecting the RC-232 and RS-422 interface, what I am concerned is about the A2NCPU communication port, before, we can used it for transferring medoc program project, but lately, the PLC or A2NCPU cannot communicate anymore to the PC, it says "no reply from PLC-system", we removed the PLC from the rack and examined it if there is a cold solder or detached any pin from the PCB by using continuity test the pins are intact and we dont find any problem on it.
The PLC is working properly except for the problem that we cannot transfer the data from medoc. please help us. Thank you.

Respectfully yours,

Edgar

The SC-02N should work. The next question is what operating system are you using. The DOS versions of Medoc can be very temperamental about comm's if you are using a non DOS system. There are a number of command line switches you could try if you are using W2K or XP. Medoc can behave very strangely under XP. I have experienced XP machines which will work perfectly well but others which will not work at all. I even have one machine which works fine with FX processors but not with A-Series PLC's.
Andybr

I'm using DOS version 2.2, and MEDOC version 1.64c, I have no problem on using on it. the real problem is on communication port or may be on the RAM/ROM I'm not sure.

In that case you might be right about the damaged port however I have never seen a port damaged by connecting a device in this way. Can the Mac communicate with the PLC?
Just out of interest, what are the communication settings in the Medoc project?
Andybr

At first MAC50 can communicate with the PLC, but now MAC50 is no longer communicate with the PLC. The communication settings for MEDOC program are the following: PLC-system=A2, bit rate= 9600, wordlength= 8, parity=odd, stopbits= 1, station=0, port= com1. this also used for MAC50 communication settings.

If the MAC cannot communicate then unfortunately the problem has to be with the port.
Andybr

I'm using DOS version 2.2

Click to expand...

are you sure about that?

did you check your PC port?
did you check the PLC programming cable with other CPU?
can you post pinout of the cable MAC <->PLC?
did you download any configuration or program change to PLC recently?

Hi Panic Mode! Yes, I checked all those you mentioned and there is no problem on them. May I asked a question?, assuming the caused of the communication port damaged is due to the static electricity coming from MAC50, what are the electronic components in the PLC can I check?

i don't have A2NCPU laying around so I can't help much.
however, any port will have appropriate driver circuitry
and A2NCPU can't be exeption. if i was going to try to fix it i would look into following:
- part numbers of all chips and get the datasheets
- any chip that is connected to port

for example RS232 devices will have some sort of RS232 driver,
RS422/485 ports will use some sort of line driver chip.

although there is tons of them, there are only few actual variations as they are mostly drop in replacements etc.

you can check online electronics stores or just google to identify "line driver" chips.

if the circuitry is SMT (probably is at leat in part even on older devices), practice soldering on something else, regadless if it works or not (anything with components of right size just to learn how to do it right, any old motherboardsm HDDs, CD drives etc are good candidates).

in some cases pcb traces are burnt and need to be repaired/replaced as well. i use enameled wire (you can buy it or just canibalize relay or small transformer). this also needs exercise, before you even think of using it on PCB, you need to verify if you can reliably and repeatably "strip" the insulation (enamel) etc. (for signals i use very thin, hair like wire so it can be soldered to smallest pins or vias. small size makes it next to invisible so it doesn't leave much clutter and it's easy to "strip" - just dip it into small drop of solder and enamel will go in smoke)

good luck