9600 Service Manual - gmecorp-usa.com

36 C-Arm Control
Technique Processor to and from Control Panel Processor
Communication between the Technique Processor PCB and the Control Panel
Processor is established during the boot process. When communication is
established all of the segments on the Control Panel Display will be illuminated
as shown below.
During normal operation, this communication link enables the Control Panel to
send commands such as kV, mA, and other user defined input to the Technique
Processor. The TXD and RTS signals from Port A of the serial communications
controller U39 on the Technique Processor PCB are sent to microprocessor U5
on the Control Panel Processor PCB. They pass through buffer U37 on the
Technique Processor PCB, through the Mainframe Motherboard and then to the
Power/Signal Interface PCB. RS422 driver U2, on the Power/Signal Interface
PCB, translates the signals to RS422 communication signals (see Figure 17).
The signals then leave the Power/Signal Interface PCB at P10 and enter the
Control Panel Processor PCB at P4. RS422 serial receiver U10 on the
Power/Signal PCB then converts the signals back to RS232 and they are
received by microprocessor U5 at pins 17 (RXD) and 44 (CTS).
TXD (pin 18) and RTS (39) from microprocessor U5 on the Control Panel
Processor PCB are translated to RS422 communication signals by RS422 driver
U8 on the Control Panel processor. These signals then leave the Control Panel
Processor at P4 and enter the Power/Signal Interface board at P10. RS422
receiver U1, translates the signals back to RS232 and they leave the
Power/Signal Interface PCB at P9. The signals then pass through the Mainframe
Motherboard and enter the Technique Processor PCB at P2.
On the older Technique Processor PCB (Assy. #876735) the signals then pass
through buffer U37 and AND gate U38 and are received by serial
communications controller U39 at pins 19 (RXD) and 27 (CTS).
On the newer Technique Processor PCB (Assy. #877744) the signals then pass
through buffer U37 and COM SELECT GAL U38 and are received by serial
communications controller U39 at pins 19 (RXD) and 27 (CTS).
RS422 DRIVER TRUTH TABLE RS422 RECEIVER TRUTH TABLE
< .05V < .05V
H 3487
3486 H
> 2.5V > 2.5V
L
3487
> 2.5V
< .05V
> 2.5V
< .05V
3486
Figure 17 - RS-422 Driver/Receiver Logic
L