Epson TM-U950 Technical Manual page 85

CONFIDENTIAL
Host interface circuit for the TM-U950P
TM-U950P printer has an IEEE 1284 interface for connection to the host computer. Control CPU (I/F
circuit board U2) controls the transmission between the host computer, and the CPU converts the
received data to the serial data, and then the CPU sends the data to the main circuit board. TTL IC (I/
F circuit board U1, U9, U10) drives or receives the interface signal. Transmission between host has
other mode, IEEE 1284 Nibble/Byte mode which is the reverse directional transmission.
Drawer kick-out circuit
The DKD_1 and DKD_2 signals from the CPU set the drawer kick-out driver transistors Q7 and
Q8 to on; they in turn output the drawer open signal. The drawer status signal DK_S is input to
the gate array, allowing the host to check the status via the interface.
The +24 V drawer power supply is controlled by the three-pin regulator (U1) which cuts off the
supply in case of excessive current.
2-40 Mechanism Configuration and Operating Principles
Figure 2-49. Device Connection Block Diagram
Rev. A