Serial to Analog Transmitter, getting very low output

Discussion in 'General Electronics Chat' started by Sakib001, Nov 16, 2015.

  1. Sakib001

    Thread Starter New Member

    Nov 16, 2015
    8
    0
    Hi guys,

    I am having some trouble in configuring a serial to analog transmitter. I have a temperature readout from which I get the data out through a RS232 port. Now I am trying to convert this data into a 0-10 VDC / 4-20 mA analog output to feed this to a temperature controller. But, does not matter how I configure the transmitter, I always get a very low voltage/current output from the transmitter. I am attaching the manual of the transmitter herewith. Any help will be highly appreciated ...

    Thanks
    Nazam
     
  2. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    4,769
    969
    and did you program it properly (and send the program to the transmitter)
    did you set the jumpers properly?
    is baud rate set properly?
    is the data in the proper format for the device?

    Have you called the manufacturer to have them walk you through the setup?

    There is very little we can do as we have no idea how you have it wired or programmed,etc....
     
  3. Sakib001

    Thread Starter New Member

    Nov 16, 2015
    8
    0
    I programmed it according to the manual.
    I set the jumpers properly.
    I set the baud rate as 9600 as mentioned in the manual.
    I am a little confused about the data formatting though ... I have called the manufacturer about it, they actually want to know an example of the actual ASCII string thats been sent to the transmitter from the device through the RS232 port. Any idea on how to get that?
     
  4. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    4,769
    969
    No.. You should know.. Its your computer (or other device with the RS232 port) thats gathering the temperature and sending the string..
    Please let us know how you are acquiring the temperatures and what program you are using to send the data over serial.
     
  5. Sakib001

    Thread Starter New Member

    Nov 16, 2015
    8
    0
    Thank you for your attention mcgyvr :)

    I am using a LabView code to get the data from the device using a RS232 to USB converter. The code receives one data point every second and whenever it receives a new data point (apart from storing it into an excel file), it sends it to a COM port of my computer. Through that COM port, I use another USB to RS232 converter to send the data point to a transmitter, which should convert it to a 4-20 mA current. But, the current I am getting in the transmitter output is very very low which does not make any sense ...
     
  6. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    4,769
    969
    ok so you should know how the serial string is formatted..
    does it match their requirements?
    have you tried to read it with a serial monitor to ensure its working as it should?

    What exactly are you measuring at the output?.. you say "low current"
    you said 0-10V or 4/20ma.. which one are you setup to output?
     
  7. Sakib001

    Thread Starter New Member

    Nov 16, 2015
    8
    0
    Dear mcgyvr,

    Thank you for all your advices.

    "ok so you should know how the serial string is formatted" thats where I'm confused. I have a requirement mentioned in the manual of the transmitter (the receiving serial port). You could find it in page-21 & 22 of the manual as attached here. I formatted the data string in my code as such before feeding it to the serial port.

    I don't know how to read it using a serial monitor. Could you please tell a little more on that?

    I have placed the jumpers in the transmitter so that it transmits an analog output in the 0-10 V range. The data I'm feeding to the transmitter is equivalent to 1.5 V now, but it is always showing a value of 0.6 V (in a multi-meter) which makes no sense to me!!! I'm so much frustrated ...
     
  8. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    4,769
    969
    start simple..
    Does the output voltage change with different temperatures?
     
    Sakib001 likes this.
  9. Sakib001

    Thread Starter New Member

    Nov 16, 2015
    8
    0
    You are spot on with the question mcgyvr ... it does not change at all with the temperature. Does that mean the serial port of the transmitter is not receiving anything??
     
  10. Sakib001

    Thread Starter New Member

    Nov 16, 2015
    8
    0
    Hiiiii mcgyvr, I have just found something very very interesting. I just downloaded a serial port monitor software. What I found is absolutely amazing, the serial port is receiving data in hexadecimal format!!! But as far as I can think, nowhere I have configured my code to send hexadecimal data!!! I am now looking thoroughly into my code to figure it out ...
     
  11. Papabravo

    Expert

    Feb 24, 2006
    10,135
    1,786
    Are you sure it is not the monitor displaying hex? If you convert pairs of hex digits to characters, do you recognize the strings?
     
    Sakib001 likes this.
  12. Sakib001

    Thread Starter New Member

    Nov 16, 2015
    8
    0
    Hi Papabravo,

    I verified that the monitor is displaying the data which it reads at the port!!! I just can't make the serial port it read the actual string that I am sending to it ... when I convert pairs of these hex digits, they get back to the original string ...
     
  13. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    4,769
    969
    Its not receiving anything useful then..

    Sounds like once you get the serial string formatted as required by the transmitter things should work as expected..
     
  14. Sakib001

    Thread Starter New Member

    Nov 16, 2015
    8
    0
    Yeah, I'm trying to do the formatting using my LabView code, but it seems that it has some issues. Could you please recommend any other way by which I can format and send the serial data to the transmitter according to the requirements?
     
  15. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    4,769
    969
    do you need excel logging?
    or what else is the computer doing?
    Why not just use a cheap temp controller with included thermocouple?
    What are you controlling?
     
Loading...