B4J Question Socket and asynstreams with ATM Terminal

Pedro Caldeira · Oct 25, 2018

Hello All,
i am writing an application (B4J) to send payment to a Ingenico atm Terminal (PinPAD)
I send the comand to pay, for instance 2.80 € and the ATM respondes by placing that value in the visor and asking for the card.
STRING TO SEND TO The ATM : S00000028000000000000000000000000
so far so good, then I cancel ou finish the operation in the PinPAD and I receive the propper data in B4J
But if I try to do another payment, i get a wrong amount size in the pinpad's reply and cancels the operation.
I talked to the uys in the ATM factory and they say that i have to clear the buffer beetween comms. or to send a byte with 0 at the end of the comms.
It is clearly a buffer problem, because if i close the App and restart it the ATM works well again.
Any suggestions ?

how can i clear the Outputstream ? or how can i send the byte with 0 in the data to send.

B4X:

FirstChar="S"
Service="0"
Dim Amount2Pay As String = NumberFormat2(TotalPayment,1,2,2,False)
Dim Line2Send As String =$"${FirstChar}${Service}${Amount2Pay}${DummyString}"$
Log("MB:" & Line2Send)
Dim Data() As Byte
Data = Line2Send.GetBytes("UTF8") 

If MB_Status = True Then
    MB_InOut.Write(Data) ' MB_InOut is the AsynStreams object
End If

Thanks

Daestrum · Oct 25, 2018

You could probably add Chr(0) to the end of the Line2Send

B4X:

Dim Line2Send As String =$"${FirstChar}${Service}${Amount2Pay}${DummyString}"$ & Chr(0)

DonManfred · Oct 25, 2018

Pedro Caldeira said:
how can i clear the Outputstream ?

what about sending a 0byte at the end?

Pedro Caldeira said:
or to send a byte with 0 at the end of the comms.

Pedro Caldeira · Oct 25, 2018

DonManfred said:
what about sending a 0byte at the end?

how ?

Erel · Oct 25, 2018

B4X:

Dim Data() As Byte
Data = Line2Send.GetBytes("UTF8")

Nicer:

B4X:

Dim Data() As Byte = Line2Send.GetBytes("UTF8")

Pedro Caldeira said:
how ?

B4X:

Dim bb As BytesBuilder
bb.Initialize
bb.Append(Line2Send.GetBytes("UTF8")).Append(Array As Byte(0))
Dim Data() As Byte = bb.ToArray

https://www.b4x.com/android/forum/threads/89008/#content

Pedro Caldeira · Oct 25, 2018

Thanks Erel,
my bad.
But still doesn't work.
If restart the Application and send the purchase it works, but one purchase after the other, I get the error, either with the BytesBuilder or the added Chr(0) solutions.

OliverA · Oct 25, 2018

Could try to send the 0 separately.

B4X:

If MB_Status = True Then
    MB_InOut.Write(Data) ' MB_InOut is the AsynStreams object
    MB_InOut.Write(Array As Byte(0))
End If

Or

B4X:

If MB_Status = True Then
    MB_InOut.Write(Array As Byte(0))
    MB_InOut.Write(Data) ' MB_InOut is the AsynStreams object
End If

Pedro Caldeira · Oct 25, 2018

OliverA said:

Could try to send the 0 separately.

B4X:

If MB_Status = True Then
    MB_InOut.Write(Data) ' MB_InOut is the AsynStreams object
    MB_InOut.Write(Array As Byte(0))
End If

Or

B4X:

If MB_Status = True Then
    MB_InOut.Write(Array As Byte(0))
    MB_InOut.Write(Data) ' MB_InOut is the AsynStreams object
End If

Already did. nothing works

Pedro Caldeira · Oct 25, 2018

now, they say that I have to append a buffer of 500 bytes initialized with zeroes. How can I do that ?

B4X:

bb.Initialize
bb.Append(Line2Send.GetBytes("UTF8")).Append(Array As Byte(0)) ' but with 500 bytes
Dim Data() As Byte = bb.ToArray

DonManfred · Oct 25, 2018

Pedro Caldeira said:
now, they say that i have to append a buffer of 500 bytes initialized with zeroes. How can I do that ?

B4X:

bb.Initialize
bb.Append(Line2Send.GetBytes("UTF8"))
for i = 1 to 500
bb.Append(Array As Byte(0))
next
Dim Data() As Byte = bb.ToArray

Pedro Caldeira · Oct 25, 2018

DonManfred said:

B4X:

bb.Initialize
bb.Append(Line2Send.GetBytes("UTF8"))
for i = 1 to 500
bb.Append(Array As Byte(0))
next
Dim Data() As Byte = bb.ToArray

Worked. thanks guys

OliverA · Oct 25, 2018

Should also work

B4X:

Dim bytes(500) As Byte ' byte array initializes to zeroes
bb.Initialize
bb.Append(Line2Send.GetBytes("UTF8")).Append(bytes)
Dim Data() As Byte = bb.ToArray

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