CP340 serial

userxyz · Mar 13, 2007

Hi,

I have and S7-315-2DP on my desk with a CP340 on the same rack.

I connected the Serial port with a standard serial-cable to Com-2 of my PC.

how should I begin, I will download the manuals of the CP340 on the siemens site, but, is it good to test a connection to the pc ?? what should I do...

I need to test a Serial communication, just to know how it works, and later (in 2 or 3 months, doing a project with it)

greetz

JesperMP · Mar 13, 2007

Are you going to use standard ASCII codes, or some protocol like Modbus or DF1 ?
If it is just ASCII, you can fire up Hyperterminal on the PC.

userxyz · Mar 13, 2007

It

It will be ASCII

hyperterminal ??? HELP !!

manmeetvirdi · Mar 13, 2007

hyperterminal

start-->Programs-->Accessories-->Communications-->Hyperterminal

userxyz · Mar 13, 2007

some snapshots

I configured the CP340 in S7:

I've chosen ASCII:

I checked the protocol in S7:

Transfer Settings: (I didn't change anything here):

Made the Hyperterminal settings identical:

every time I hit a key (when hyperterminal is connected) I see the RXD led blink on the CP340, so there is data exchange.
I've installed the software for CP340, so I have the standard CP ptp blocks:

Now, how do I config such blocks in S7 ?

userxyz · Mar 13, 2007

hey

I found a sample project CP_340_ptp_Com_CP34x
I'll try it first...

Can u read out data with hyperterminal ?

s7xp.com · Mar 13, 2007

You need two FB to communicate. Send and receive. Please check the sample program first.

userxyz · Mar 13, 2007

Some more snaps

So I used the send block to send something to the PC

I send the value 73 and receive I in ASCII.

Now I'm gonna use the opposite, sending from the hyperterminal to the S7,

can I convert ASCII to Decimal in some way in the S7 cpu ?

S7Guy · Mar 13, 2007

Combo, to make your life much easier when dealing with ASCII comm in S7, set up your DB with an array of CHARs. That way, you can monitor the DB online and see the actual ASCII values.

Open up your DB, make a variable called something like "Message", and make it an array of type CHAR, from [1..1024] (or whatever reasonable values are for you).

Also, there are better apps than Hyperterminal for what you are doing. I like Eltima, but there are other free ones out there: http://www.eltima.com/products/serial-port-monitor/?gr=sniffer&gclid=CL65pYea8ooCFQtpGAodQQUUpw

userxyz · Mar 13, 2007

made standard block of it for myself:

And tested in a vat:

71 69 82 82 89 is my name that I send to Hyperterminal, and I receive GERRY

115 100 107 89 were 4 keys that I pressed at the same time

This is what settings I connected on the outside:

So, I must say, thanks all so far !!!!!

Okay, I made chars instead of decimal numbers in my Vat, thanks S7Guy:

Now, here comes my last step...

I will receive analog values that will be given in ASCII to my S7 PLC on the CP340 card. How can I convert ASCII/CHAR to Decimal values ?

Can I c

S7Guy · Mar 13, 2007

To convert individual ASCII values to decimals, just subtract 48 from each digit. For instance, ASCII "5" is actually a 53.

Once you do that, you will have to do some math to interpret the ones place, 10s place, 100s place, etc, but that is easy.

I think Siemens also makes a canned function for this, but you can do this quite easily as well.

userxyz · Mar 14, 2007

I'm not sure how they will give the values to me...

The project is: 24 sensors grouped in 4 sensors / tds box. each box has a RS485 serial communication. To be a bit ready for serial communication, I did this test with a CP340.

4 analogue values wil be given / box. Each box has it's own adress...

See the attachement also...

any idea how the values will look like ?

I don't have the tds boxes yet, so further tests are not possible

userxyz · Mar 14, 2007

hey I got more info

it will be 4 values in ASCII like this:

A175B211C566D222

A = 17,5 degrees
B = 21,1 degrees
...
...

like that.

on RS485, not ptp

each box has an other request code

s7xp.com · Mar 14, 2007

I think you are right. It is a simple ascii protocol. With the RS485 interface you may read out all TDS units with one CP340. Poll the units cyclic. Only there is no error checking in this protocol, so if a bit "fall" due interference or something you will receive wrong data.

userxyz · Mar 15, 2007

...

So, if there is a fault, the data may not be sended into my program...

that's a good idea

then I'll make a HMI alarm for it

CP340 serial

userxyz

Member

JesperMP

Lifetime Supporting Member + Moderator

userxyz

Member

manmeetvirdi

Member

userxyz

Member

userxyz

Member

s7xp.com

Member

userxyz

Member

S7Guy

Member

userxyz

Member

S7Guy

Member

userxyz

Member

userxyz

Member

s7xp.com

Member

userxyz

Member

Similar Topics