Lp 633 Input Board; Description - Fresenius Medical Care 4008 E Technical Manual

8.13 P.C.B. LP 633 Input board
8.13.1

Description

Address coding (circuit diagram 1/7)
P.C.B. LP 633 (input board) is directly connected to P.C.B. LP 631 (CPU 1) via the address bus,
the data bus, and the control bus.
IC2 buffers the control bus, which consists of the /WR/RD and CS_INPUT signals.
The address bus and the data bus are buffered by IC 1 and IC 3. They are cut off highly resistive,
as soon as H level is applied to the CS_INPUT signal at IC 2, pin 9. An L signal at IC 2, pin 9,
releases ICs 1, 3 and 4. IC 4 decodes the addresses (4-to-16-line decoder). The decision, which
outputs turn to L level, is taken by the address data at inputs A to D. The L signal releases the
connected module. The ADCx_ALE and ADCx_OE signals are generated by IC 9 and IC 10 by
means of the CS_ADCx, WR and RD signals.
ADC oscillator (circuit diagram 1/7)
IC 8 constitutes the oscillator for the analog-to-digital converters.
Serial receiver (circuit diagram 1/7)
At the moment, IC 6 is not needed. It will be used for data transmission (serial/parallel conversion)
with the new level detector module.
External alarm (circuit diagram 2/7)
A voltage (AC voltage or DC voltage of 20 V to 40 V) can be applied to pins X633L/24b and
X633L/25b. Rectified by GL1, this voltage generates the EXT_ALARM signal at OC1, pin 5.
Driver (circuit diagram 2/7)
The digital input signals are applied to driver modules IC 13 to IC 16 as well as IC 19 to IC 21. The
driver modules are activated by the RD and /CS_LATCHx signals being applied.
IC 17 and IC 18 are provided as voltage converters (12 V → 5 V).
IC 45 constitutes a retriggerable single-shot multivibrator, which is triggered by the optical
detector in the level detector module via the OD_IN signal at X633L/8c (frequency approx.
90 Hz).
Analog-to-digital converters (ADCs) (circuit diagram 3/7)
Via voltage dividers, the analog input signals are applied to the inputs of the A-D converters. The
reference voltage for the ADCs, which is generated on CPU 2, is driven by IC 22 (5, 6, 7).
Conversion of the analog input signals is started by the H-active ALE signal and can be read in
after the conversion by applying the H-active OE signal.
Fresenius Medical Care 4008 4/09.03 (TM)
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