Redlion voltage levels to receive data for rs 232 communication

bjrajendra

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Hello all,
Actually I am sending a character from my DSP processor to my hmi (REDLION ) with voltage levels +5v and -5v ( I checked my voltage levels using oscilloscope ) and i wrote a program in crimson to receive the character ( using portinput() function ) whatever i send the character with my DSP , the character was not receiving on my REDLION display and nothing it was showing, but the same thing is working with PC whose voltage levels are +10v and -10v and my redlion display is showing the character i send from my hyper terminal . Is there any restriction on voltage level for the REDLION for RS232 communication.

hope someone will solve this problem,
thanks,

B J RAJENDRANATH
 
I believe Red Lion adheres to the +-3V (minimum) RS-232 specification so the +-5V should be fine.

Since RS-232 is single-ended, are you hooking up the common (ground) pin between the sender (DSP) and receiver (Red Lion)?
 
I am using a db9 connector on DSP side with rx,tx,gnd pins connecting to rj12 of my HMI for rs232 communication, and I am sure that redlion rx-tx connected to tx-rx of DSP
 
Attached image of comm pinout just to be sure.

You said Hyperterminal works - with the same cable?
What are the parameters you used for portinput()?
May be something as simple as Hyperterminal supplys a Carriage Return at the end of the string that the Redlion is responding to and the DSP does not.

Parameters:
PortInput(port, start, end, timeout, length)

If you have no leading info to trim set start to 0.
If you are looking for Carriage Return set end to 13.
If no Carriage Return/End character or you want to use a pre-defind string length then set end to 0 and you will need to set the length or timeout to ensure the comm is not sitting waiting for Carriage Return/End Character.

If I know has Carriage Return typically I use PortInput(port#, 0, 13, 0, 80); for string smaller than 80 charachters.
If no Carriage Return I will use PortPrint(port#, 0, 0, 200, Str_length);

redlion.jpg
 
Attached image of comm pinout just to be sure.

You said Hyperterminal works - with the same cable?
What are the parameters you used for portinput()?
May be something as simple as Hyperterminal supplys a Carriage Return at the end of the string that the Redlion is responding to and the DSP does not.

Parameters:
PortInput(port, start, end, timeout, length)

If you have no leading info to trim set start to 0.
If you are looking for Carriage Return set end to 13.
If no Carriage Return/End character or you want to use a pre-defind string length then set end to 0 and you will need to set the length or timeout to ensure the comm is not sitting waiting for Carriage Return/End Character.

If I know has Carriage Return typically I use PortInput(port#, 0, 13, 0, 80); for string smaller than 80 charachters.
If no Carriage Return I will use PortPrint(port#, 0, 0, 200, Str_length);
I wrote like this
portInput(port#,0,13,1000,1)
ie.,within the time 1000ms it has to receive 1 character it doesnt see 13 as i kept the time and length and i really don't know Carriage Return play a role in this.Is it that much important as I kept the length and time ? and any way my DSP is sending only tx,rx,gnd.
REGARDING CONNECTIONS :
Earlier I had connected like the image shown and my hyperterminal to redlion worked,then i connected only tx,rx,gnd from db9 (HYPERTERMINAL) to rj12 (REDLION) then also it worked.
 
I had updated to latest version of Crimson 3.0. It had "corrected" a previous issue with the port input function. After updating a G315 with a wireless RS232 barcode scanner, I received no more data from scanner. Called Redlion, and I believe Jeremy verified that this fix actually created a new port input function issue. I had to roll back my version to the next oldest until there is a new update. After rolling back, port input function worked again. This sounds similiar to my problem.
 

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