code: function _serverDebug(text, unitID, functionCode, responseBuffer) {
      // If no responseBuffer, then assume this is an error
      // o/w assume an action
      if (typeof responseBuffer === "undefined") {
          modbusSerialDebug({
              error: text,
              unitID: unitID,
              functionCode: functionCode
          });
  
      } else {
          modbusSerialDebug({
              action: text,
              unitID: unitID,
              functionCode: functionCode,
              responseBuffer: responseBuffer.toString("hex")
          });
      }
  }
docs: Helper function for sending debug objects.
  
  @param {string} text - text of message, an error or an action
  @param {int} unitID - Id of the requesting unit
  @param {int} functionCode - a modbus function code.
  @param {Buffer} requestBuffer - request Buffer from client
  @returns undefined
  @private