wtf4 rs232-USB

[tian66]

I am uising null mode cable. I searched on the website and the staright through type will not work

[tian66]

I did ask Watlow and they told me use Comm 7 to test the connection. But it still failed and they cannot tell the reason through the phone...

Thanks!

[RavensFan]

Well, if there software doesn't work, then it is obviously not a LabVIEW problem or an NI problem.

You were asked earlier in the message thread if you have read the communication manual, but there was no clear answer that you had.

I found this http://www.cszindustrial.com/portals/1/pdf/WatlowF4_UserManual.pdf from an simple Google search.  Page 12.10 talks about the communications cable.  It also shows wiring for an RS-485 connection and an RS-232 connection.  Are you sure you are using RS-232?  In this case, you can't really say you should be using either a straight through or a null-modem cable because the connection on the controller side is not a DB9, but a terminal strip that you feed stripped wires into.

I suggest reading the manual, searching on Google, and searching the Watlow website www.watlow.com

[tian66]

Thank you for your answear.

I did read this manual and also called Espec and Watlow to confirm the connection.

I am sure I am using the RS-232. There is a RS-232 DB9 male on the chamber and it is clearly labled RS-232. So I bought a NULL modem cable and a RS-232(male) to USB. The connection coming out form the Chamber is RS232 male(on the chamber) ---> NULL modem ---> RS-232(male) to USB--->Laptop.

I did not quit understand what do mean the connection on the controller side is not a DB9. You mean the terminal on the Espec is not a real RS232?

I need to narrow down my question. Is a RS232 to USB a proper cable? Espec told is not. But from your advices, it might be and I should dig further.

I have limited on the rs232-usb communication. Most of devices I am using are simple to setup. Examples and straightfoward tip sare appreciated.

[RavensFan]

DB9 is a definition of the connector on the end of the cable, or the port on the device.  It is the rounded trapezod shape that has 9 pins with 5 on top and 4 on the bottom.  It can be male or female.  It has nothing to do with RS-232.  DB25 (a 25 pin connector) also exists and has specified pinouts for RS-232 ports.  (Also a pinout for a parallel printer port.)

RS-232 defines the electrical interface of the interconnect wiring.  It doesn't have a male or female designation.  For RS-232 it is a single receive, a single transmit, and a single ground wire.  Transmit and Receive are separate wires that are referenced to the ground.  RS-485 and RS-422 are two other specifications where the communication wires are a differential pair referenced to each other.  It could be a single pair that handles both sending and receiving, or two different pairs.  The specs also define the voltages that determine whether a signal is a binary 1 or 0.  The specs also define other lines that may or may not be necessary such as the handshaking lines.  For a device such as an external modem, the pinouts of the transmit and receive, and the handshaking lines are already swapped within the port, so only a straight through cable is needed.

Straight through vs. null modem defines the way the wires on each end of the cable are connected.  If you are connected two PC's, they are going to have identical pinouts, so you need a null modem cable that crosses the wires so that the receive pin of one goes to the transmit terminal of the other and vice versa.  Handshaking lines are also crossed.  On a DB9

The picture I saw of the device did not show a DB9 connector, it showed a terminal strip.  So null modem vs. straight through really doesn't apply.  Rather than pins 2 and 3 on a DB9 connector (and which transmit and which is receive determines what type of cable you need), the terminal strip has transmit and receive are on a terminal strip way out at pins 14 and 15.

If you are truly set up to be RS-232 on that device, than an RS-232 to USB cable is fine.  You just need to make sure the cable you use to wire from the DB9 on the USB/232 convertor is wired properly to the terminal strip on the device.

Yes, you need to dig further.  Draw a wiring diagram of all the pinouts if you need to.

[LTS]

Thank you!

[tian66]

Thanks!

[tian66]

To make it clear. What we bought is a Espec Chamber and it has the Watlow f4 controller insides the chamber.

The terminal we can see from the chamber is DB9 and we are not able to rewire the controler terminal. On the Espec chamber manul, they label this terminal as rs232 terminal (manul page 40-45)

Very appreciate for your detailed explanation.

[RavensFan]

Several schematics there.  Some are hard to read because the text bleeds together.  It isn't clear what is going on.

That connector in the picture is definitely DB9 male.  It looks like it was made and installed by Espec who built this master box.  So they should know how it is wired.  It is weird that they have an aluminum plate screwed into that front cover in a way that covers the bottom half of the word "communications".  Page 45 shows part #1 to a small box that has some lights on the front and a GPIB port as an output.  The drawing says GP1B  (that should be the letter "I", not the number one) to Modbus communications option.  So is this some sort of converter?  I don't think I've ever heard of a modbus GPIB converter before.

Page 43 shows a Watlow F4 humidity instrument with something that sort of looks like a thermocouple plug and socket.  ????  Page 12.8 of the earlier link shows this to be a analog voltage output.   Nowhere do I see in the pages 40-45 something that shows the Watlow connected serially to that DB9 connector.

I don't think you are actually set up the way you think you are.  You are going to have to talk to Espec more and hopefully find a person who has a clue.

EDIT:

When you say pages 40-45, what pages are you referring to?  Are you talking about the page number within the PDF, or the page number that is on the scanned papers?  Page 40 of the PDF goes to a page with the number 36 at the bottom.

If I look at pages 40-45 of the scans, (pages 44-49 of the PDF) there are some differences.

Page 48 of the pdf shows that connector going to an RS-232 to ethernet device (#2).  It shows a null modem adapter (#1) in the middle of that cable.  If that is the case, then you should probably be using a straight through cable between your USB/232 adapter on your laptop to the connector on the front of the cabinet.

Also check on the writeups around those pages.  Verify which option you truly have and read up on it.  Some of the text near those schematics describe how to establish and verify communication.

[tian66]

The page numbers are referred to the page number within PDF.

Yes they did showed how to settup the rs232 to ethernet.

I called Espec and a technician said the rs232 to usb should work. But I called Espec yesterday again, another technician told me the RS232-USB will not work.

I think I should try ethernet cable but not spend more time on RS232. This question has beyond the scope of LabVIEW forum.

Thank you for your help!