Chapter 2 THEORY OF OPERATION
2 - 12
J11-3 is “TXD(OUT).” It is ESD protected by R21, Z7 and C7. It comes from U3B-4 which
buffers the signal “RS232_TXD” from J2-6.
J11-4 is “RTS*(OUT).” It is ESD protected by Z6 and C6. It comes from U3D-10. U3D-9
connects to “RTS*” via J2-8.
J11-5 is “CTS*(IN).” It is ESD protected by Z5 and C5. It is pulled up to +5V by R7 and
isolated by R8 into U3E-11. From U3E-12 it goes through MUX U4C-8 to U4C-9 to CTS*
on J2-9.
J11-6 is “VPP[12V] (IN).” It is ESD protected by Z3 and C3. It is pulled low by R4. It
provides the programming voltage for the FLASH memory and controls the “MAS_EA*” line
of the master CPU.
J11-7 is not connected.
J11-8 is the “CHARGER-(IN).” It is ESD protected by Z2 and C2.
• RS-232-C (DB-9 Port)
The RS-232-C communication port is provided for monitoring and control of the pump. The
pump’s configuration is also downloaded via this port. RS-232-C communication is
facilitated by U5. It is a self contained voltage generating serial port. It takes the +5 volt
supply and makes +9V and -9V using capacitors C16, C17, C14, and C15. The device is
controlled by “EIA_IN” from J2-11. This control line shuts down the voltage converters and
puts the device in a low power state with tri-stated outputs. This control line also acts to
disconnect the active inputs from CMOS inputs on J11. The signal outputs are always
present on the CMOS output even in RS232 mode. The signal inputs are selected by the
“EIA_EN” which controls U5-18, the “ON/OFF” input.
U4A is configured as an inverter to invert the active level of “EIA_EN” to operate MUX’s
U4B and U4C.
J14-1 is an NC.
J14-2 is “TxD” and is ESD protected by R15, C22 and U6B.
J14-3 is “RxD” and is ESD protected by R14, C21 and U6A.
J14-4 is an NC.
J14-5 is connected to “GND”.
J14-6 is an NC.
J14-7 is “RTS” and is ESD protected by R16, C23 and U6C.
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