I’m make JPOS request for iso8583 and use code:

String FileParam = "jpos_fields.xml";
    
GenericPackager packager = new GenericPackager(FileParam);

 ISOMsg isoMsg = new ISOMsg();
        isoMsg.setPackager(packager);
               
        isoMsg.setMTI("0800");
isoMsg.set(3, "990000");
        isoMsg.set(7, "0605144125");
        isoMsg.set(11, "000001");
        isoMsg.set(24, "831");
        isoMsg.set(29, "001");
        isoMsg.set(41, "S01JS020");
        isoMsg.set(42, "0187490");

 isoMsg.recalcBitMap();
        BitSet bset = (BitSet) isoMsg.getValue(-1);

 TPDUChannel channel = new TPDUChannel();
        channel.setHost("127.0.0.1");
        channel.setPort(8185);
        channel.setPackager(packager);
        
        byte [] TPDU = new byte [5];

        TPDU [0] = (byte) 0x68; //0800/0810 only
        TPDU [1] = (byte) 0x00;
        TPDU [2] = (byte) 0x03;
        TPDU [3] = (byte) 0x02;
        TPDU [4] = (byte) 0x00;

channel.setTPDU(TPDU);

    //channel.pr
    
    channel.connect();
    channel.send(isoMsg);
    
    ISOMsg r = channel.receive ();
    channel.disconnect ();
    
    BitSet bsetRe = (BitSet) r.getValue(-1);`

And TPDUChannel class:

public class TPDUChannel extends ASCIIChannel {
  
    private static byte[] TPDU = new byte[5];
    
    public static void setTPDU(byte[] b) { 
        System.arraycopy(b, 0, TPDU, 0, TPDU.length);
    }
    
    protected void sendMessageLength(int len) throws IOException {
        // write TPDU
        if (TPDU != null) serverOut.write(TPDU);
        //write ASCIIChannel length
        super.sendMessageLength(len);
    }

    protected int getMessageLength()  throws IOException, ISOException {
        // skip header
        if (TPDU != null) {
            byte[] b = new byte[TPDU.length];
            serverIn.readFully(b, 0, TPDU.length);
        }
        // read ASCIIChannel length
        return super.getMessageLength();
    }

}

It’s work fine and I get an answer, but it’s need to make manual request by socket. I know how to gen isoMsg and send over socket, but really don’t know how to set TPDU. Please, help

Try manual send socket request like JPOS