POS Hypercom Terminal T4230 integration issue using Java serial PORT communication

Question

We are integrating JDE-Edwards ERP to POS terminal using the Java integration Code but when I tried to send the transaction initiate request to the POS terminal it is working sometimes fine and sometimes I am getting the negative acknowledgment from the POS.B ut the request which I am sending is same in both scenario. I am unable to figure out where is the problem. I have taken the low-level traces of com port communication using the Eltima software but there is no difference. Here the POS terminal which I am using is HyperComm T4230

I have tested my same code VX520 Pos terminal it is working fine and it is not working on this terminal.

Request I am sending it while initiating the transaction.

static byte[] sendData =
    { 0x02, 'P', 'U', 'R', 0x1c, '1', '0', 0x1c, '9', '9', 0x1c, '0', '0', '0',
      '0', '0', '0', '0', '0', '0', '1', '0', '0', 0x1C, '6', '3', '4', 0x1C,
      ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ',
      ' ', ' ', ' ', ' ', ' ', ' ', ' ', 0x1C, ' ', ' ', ' ', ' ', 0x1C, ' ',
      ' ', ' ', ' ', ' ', ' ', 0x1C, ' ', ' ', ' ', 0x1C, 0x03 };

I am expecting it should not be stuck while the user initiated the transaction from the JDE ERP.