Is there a way to DDEPoke a value greater then 9 into a PLC?

NashG · October 10, 2017, 6:57pm

I need a way to enter recipes into a Rockwell PLC from a spreadsheet. The DDERequest inputs the current values flawlessly, but when I try to output the new values using DDEPoke all that is transmitted is the first character. If I enter a value of 256 DDEPoke only transmits the 2 and truncates the remainder of the number. I can also use RSLinx to copy a DDE link to the clipboard and then use Paste Special to paste the DDE link into a cell. But I need a script that will write a minimum of 5 digits back to the PLC.

Atom_Automation · September 5, 2018, 12:47am

Esta es la conexion a RSLinx,

tiene un problema solo escribe un caracter, por si alguien sabe por que lo hace de esa manera
la lectura o Requuest, si lo hace de varios caracteres

Sub Main

Dim nDDeChannel as integer
Dim s as String
     rem este es un comentario
     rem este es TOPIC = "Template_Osmosis"
nDDeChannel = DDEInitiate("RSLINX","Template_Osmosis")
if nDDeChannel = 0 then
	Print " Fallo de Conexion "
else
	rem Esta es la Varible a la cual se escribe =  "Monitor1"
	rem Esta es la Varible a la cual se escribe =  "Status"
	rem Estas dos variables hay que generarlas en el controlador
	DDEPoke(nDDeChannel,Item := "Monitor1",data:="2450")
	s = DDERequest(nDDeChannel,"Status")
	DDETerminateAll      
end if

End Sub

mathieugalardo · October 16, 2025, 2:24pm

Hello,
I’m trying to do the same thing and I have the same issue (only “2” is sent to PLC when I try to send “256” for example.
The DDERequest to read PLC values tags works fine but not the DDEPoke…??
Thank you,

mikekaganski · October 16, 2025, 2:58pm

Is there a bug report for that, where a developer can see the problem - with exact steps to reproduce?

koyotak · October 17, 2025, 7:47am

This might help: Shifting the top digit “2” after its input (MSB: most significant bit) from the ones place to the tens place (multiplied by 10 OR shifting to the left), input the next lower digit “5”, multiplying both by 10 OR shifting to left) so that the ones place is “free” (filled with ZERO) and input the low digit “6” (LSB: lowest significant bit) (to the ones place). This is a standard procedure that every programmer understands from digital technology. Reason: PLCs operate/calculate with numbers in floating-point topology and cannot “recognize” multi-digit integers as such. You might need to implement a recognizing OP-block instead.