RS232-Hyperterminal

Hello Everyone,

After reading and searching some topics here about RS232 Communication troubleshooting,I wanted to test it myself,so I hookedup my computer to DL340 koyo and opened hyperterminal to see what happens and if I can get any data sent by PLC..nothing
Am I supposed to receive anything here??
the main porpuse of this experiment is to check the communication cable through some basic software rather than Directsoft or Tisoft..Just for my own knowledge..

Thank you

The only way you can test anything with Hyperterminal is if the plc supports ASCII. The DL340 does not. The protocols require that the software on the other side start the negotiations, so that is why you do not see anything. It is impossible to type fast enough to keep up with the protocol requirements without timing out.

Directsoft or TISoft are the way to go.

The port on the PLC is generally a 'slave' port. That politically incorrect term means that it only does what it is told to do. It only responds to requests from a communications 'master'. When you connect Hyperterminal to it, the Hyperterminal application can be the master. In order to do that, you need to know how to put together a communications request. Unfortunately, its not as simple as typing in "Send me the current state of inputs 000 through 077". There are multiple steps involved, and you have to include a 'checksum' (integrity check) as part of the message.

Furthermore, the methods involved in modifying the ladder logic are not published, so abandon hope of using Hyperterminal as a substitute for Direct Soft.

Thanks alot guys.

To simply test cables you can make device like shown here.
I made it (actually I let our electrician do it ) using very
common parts. Reason I went for DIP switches, resistor network
and LED cluster is just to save space and time to put everything
together. Master is only ca twice the size of 9V battery and
Slave is about half the battery size. The comercial unit we used
before was ca shoe-box size and quite heavy

I wanted something that is:

1. very very small - so it fits in my over-crawded bag.
2. in two pieces - so I can test cable that is already
installed on equipment with ends far appart.

Actually we have now few of them because they are so usefull.
Newer version include additional power switch because the DIP
switches get accidentally turned on and drain battery.
Also there are couple of plugs on both master and slave
(DB9F, DB9M, RJ45, M12 connector for sensor cables and screw
terminals to add any other style of connector when needed)
and we printed nice label with few common cable pinouts.

Since we have to make custom cables all the time, this little
device was many times worth the money we have spent on it
(well it was only couple of bucks anyway ).

What do you do for common if two ends of cable are far from each other?
Don't they have to have same common?

silly Question

What to use for common? Anything...
Usually there is a reel of wire or cable in the
maintenance shop or in the box with all tools...
Even extension cord (ground wire for example).
The thing is you just need single conductor.
If you have both master and slave in same unit,
you need actual 1:1 cable in series with the
tested one. This means that ends must have same
connectors as testeed cable and that's not always
available. 10-15meter of #22 wire with bare ends
is way smaller than 4 cables of same length with
connectors on each end.
Or you can use one of the conductors of tested
cable (you just put nice little jumper on both
master and slave).
Believe me, once you have tried to this little device
to figure out pnout of some unknown cable, you will know
it's value...
Originally I planed to put rotary 10pos selector sw.
which is great for shop use. I like the mini version
because it means less luggage when going to field.

atatari said:

Hello Everyone,

After reading and searching some topics here about RS232 Communication troubleshooting,I wanted to test it myself,so I hookedup my computer to DL340 koyo and opened hyperterminal to see what happens and if I can get any data sent by PLC..nothing
Am I supposed to receive anything here??
the main porpuse of this experiment is to check the communication cable through some basic software rather than Directsoft or Tisoft..Just for my own knowledge..

Thank you

Click to expand...

There's a free utility that you can use to download your program without the need for DirectSoft.

http://www.hosteng.com/SW-Products/SP_Demo_Utilites.htm

And you can get the demo version of DirectSoft from AutomationDirect. Consider buying it though, it is one fine package.

As for the connection, DS (DirectSoft) establishes itself (if necessary). So get either package and let the software do the talking.

As for the connection, the programming port (the top one) continuously transmits and receives. This is the connection that talks to DS. There are all sorts of serial eavesdroppers designs on the net, I'll leave that as an exercise to the reader


Ok, maybe not:

http://www.downloadfreetrial.com/development/deve4225.html
http://www.rs232pro.com/
http://www.kmint21.com/serial-port-monitor/


And since "reverse-engineering to achieve compatibility" is fair use (and the title to the next link), you are well within your rights to do this (this week).

http://www.lgu.com/publications/softcopy/22.shtml


As for the secondary port, it can talk Modbus or ASCII. AutomationDirect has a very nice manual for about $20 (that's what it was when I bought it years ago) that does a good job of explaining how this works.

Enjoy,


John