Cable connection between a PC and a sewing machine

#The present invention pertains to a cable connection between a personal computer (PC) and a sewing machine for transmitting data consisting of various voltage levels, wherein the cable connection has an RS 232 C port for connection to the PC, and the sewing machine has a TFL (transistor transistor logic) port.

#Electric cable connections of this type between a PC and a sewing machine are generally known. They serve to enable data transmission between the PC and the sewing machine. However, data transmission is guaranteed only if a suitable voltage level is applied to the device receiving the data.

#If the PC has an RS 232 C port, it is designed for a voltage level of -15 V to +15 V. Since the sewing machine used is equipped with a TTL (transistor transistor logic) logical unit, and thus it carries a voltage level of 0 to +5 V at its port, an additional port on the sewing machine, which would have to be designed for a voltage level of -15 V to +15 V, would be required for using a standard cable connection between the two devices. However, this requires an additional expense in connection with the manufacture of the sewing machine. Since such a PC port is used only in a small percentage of the sewing machines sold, such an increase in the cost of manufacture is not acceptable.

#In the drawings:

#FIG. 1 is a schematic representation of a sewing machine with a Personal Computer connected via a cable connection,

#FIG. 2 is a partially cutaway representation of the jack of the cable connection, and

#As is shown in FIG. 1, a sewing machine 1 is connected to a Personal Computer (PC) 3 via a cable connection 2. The cable connection 2 serves to transmit data from the PC 3 to the sewing machine 1 and vice versa. The cable connection 2 is connected, at one end, to a 25-pole connector, not shown, of the PC 3 via a 25-pole jack 4. This port is a prior-art port designated by RS 232 C (the RS 232 C standard). The other end of the cable connection is connected via a 7-pole connector 5 to a 7-pole jack 6 of the sewing machine. While the PC 3 carries a voltage level that can be varied between -15 V and +15 V on its port, the port of the sewing machine has TTL level in this case because of the logical unit used in the sewing machine control, i.e., a voltage level that can be varied between 0 V and +5 V is present on the jack 6.

#The two devices (the PC 3 and the sewing machine 1) cannot consequently be connected by a simple transmission connection. It is necessary to first adjust the voltage level of the PC 3 to the voltage level of the sewing machine 1.

#To adjust the levels of +3 V to +15 V for the logical "0" and of -3 V to -15 V for the logical "1" in the PC 3, and to adjust the TTL levels of +0 V to 0.8 V for the logical "0" and of +2.4 V to 5 V for the logical "1," which latter levels are used in the sewing machine, a level converter is integrated within the jack 4 of the cable connection 2.