The A154BB Buffer Board is used extensively to provide system compatibility with interface logic levels and to drive long cable runs as well as provide terminal block connections for Binary/BCD outputs and other signals of the A169LD/1-2 Load Cell Digitizer to hard wiring of PLC I/O's and other devices: but also contains the necessary circuitry to translate voltage and current levels from 5v to 10,12, or 15v. The outputs are addressable high impedance tri-state devices.  The A154BB is available in two models, inverting (option A) and non-inverting (option B). and can be used with other compatible devices.  It will allow cable runs in excess of 50 feet for 5v logic systems and others.

The A154BB has provisions for jumper selectable addressing for both inverting and non-inverting logic.  Up to 15 buffer boards can be addressed.  The A154BB "UP" translates from a low voltage to a high voltage  normally (i.e. TTL to CMOS): but can "DOWN" translate from a high to a low voltage (i.e. CMOS to TTL).  The input thresholds of a buss system can be shifted to TTL compatibility and no sequencing is required on power systems or inputs.  The A154BB operates at voltages from 3.0v to 15v and is capable of driving 16 low power TTL loads, 15 HTL loads or 9 low power SHOTTKY TTL loads. The input currect requirements are low (1 microamp or less).

When used with the A169LD/1-2 Digitizer in the BCD mode, the A154BB provides the following signals:

DATA VALUE SIGNALS:
                     A169LD/1-2                A154BB                        A169LD/1-2                 A154BB
                           D1B1 (LSB)                  1                                   D3B4                             11
                           D1B2                             2                                   D3B8                             12
                           D1B4                             3                                   D4B1                             13
                           D1B8                             4                                   D4B2                             14
                           D2B1                             5                                   D4B4                             15
                           D2B2                             6                                   D4B8                             16
                           D2B4                             7                                   D5B1                             17
                           D2B8                             8                                   D5B2                             18
                           D3B1                             9                                   D5B4                             19
                           D3B2                           10                                   D5B8                             20   

The A154BB can of course be used with other devices for other types of data and has 25 inputs and 25 outputs available for the purpose.

STATUS SIGNALS:
                           A169LD/1-2                            A154BB
                              OVERLOAD                            21
                              GROSS/NET                           22
                              LB/KG                                      23
                              NEGATIVE                              24
                              VALID                                     25

CONTROL SIGNALS:  The A154BB has provisions for 5 remote signals that can be used for control.  One of these can be jumper selectable as addressable or active at all times (i.e.41).

                          A169LD/1-2 OPT.A                A169LD/1-2 OPT.B                 A154BB
                               TARE                                         TARE                                      37
                               HOLD                                         HOLD                                     38
                               NET/GROSS                             NET/GROSS                         39
                               LB/KG (FUTURE)                     LB/KG (FUTURE)                 40
                               CHECK                                      CHECK                                  41

Active levels of the signals to/from the A169LG/1-2 are indicated with the convention of positive logic. That is, signals that are underlined are active for a low level, while others are active at a high level.

ADDRESS LINES:  The BB has provisions for four-bit address lines, jumper selectable for options "A" or "B".  Option "A" for inverted logic Low true and Option "B" for non-inverted logic High tru

                               ADDRESS LINES                             A154BB
                                       2(0)-1                                                31
                                       2(1)-2                                                32
                                       2(2)-4                                                33
                                       2(3)-8                                                34

NOTE: TERMINALS 26 THRU 30 ARE NOT USED. 35AND 36 ARE SPARES. 42 IS FUTURE, 43 IS +VCC, 44 IS +VDD, AND 45 IS GND.

The A169LD/1-2 signals fall into three main groups: Data values, Status Signals, and Control Signals. The four-bit Address Lines (i.e. 1,2,4,8) are for optional use.

DATA VALUES are binary related components (B1,B2,B4,B8) of each digit (D1-LSD, D2, D3, D4, D5-MSD) in the 5 digit value.  In addition, there is one line dedicated to the polarity (i.e. NEGATIVE).

STATUS SIGNALS are mode indicators of the front panel functions and information LB/KG, GROSS/NET/ OVERLOAD (-FFFF1-2). In addition, VALID is a status signal of "DATA VALID" that is active (Low Option B) then the tri-state output ports have been updated with the results of a just completed conversion in the A169LD/1-2. It is a pulsed gating signal.

CONTROL SIGNALS are active Low for input to the A169LD/1-2 and remain inactive unless used.  HOLD inhibits change in output data and holds the last reading until released (i.e. HOLD Option B).  LB/KG is not installed, this is for future software modifications. TARE is a toggle function as is NET/GROSS and CHECK (i.e. NET/GROSS, TARE, CHECK Option B).  Some signals are not used it the A154BB such as output disable which puts the status signals and data values into tri-state mode when driven high.  This forces the buss to a high impedance state, but sequential operation of conversion is not inhibited.  This function and some status signals such as CENTER OF ZERO are only available through interfacing directly with the A169 or A166TB.

The A169LD/1-2 is 4-bit addressable from a connector on the rear and is not addressed when used with the A154BB (i.e. address pos. 0).

Remember Option "A" is the inverse of Option "B" and except on special order the data values are the inverse of the controls signals.  Also, remember the A169LD/1-2 has an output that is switch selectable as High True or Low True and that it can be binary or BCD. For a one to one positive logic interface use Option "B", and for an inverse negative logic interface use Option "A".

NOTE: THE DATA VALUES AND STATUS SIGNALS CAN BE SWITCH SELECTED ON THE A169LD/1-2 AS HIGH TRUE OR LOW TRUE, BUT THE CONTROL SIGNALS ARE PULLED HIGH AND ARE ACTIVE LOW INPUTS (i.e. HOLD, LB/KG, TARE, NET/GROSS, AND CHECK). THESE SIGNALS ARE INPUTS TO THE A169LD/1-2 AND MUST BE CONSIDERED CAREFULLY.

                                                        A154BB BUFFER BOARD

*OPTION "A" IS USED IN INVERTED LOGIC BUSS ORIENTED SYSTEMS.
*OPTION "B" IS USED IN NON-INVERTED LOGIC BUSS ORIENTED SYSTEMS.

The A154BB is a circuit board that contains a 50 pin (2 rows of 25 pins each) connector for ribbon cable, 45 terminal blocks, and a 50 pin edge connector (2 sides of 25 pins each).  The board measures 6" x 10" x 1-1/2" high and can be mounted in any position to a back pan. The terminal blocks are barrier type strips for up to four 18 AWG or two 14 AWG wires each.  The 50 pin edge connector is the interface I/O and the 50 pin ribbon connector output is in parallel with the corresponding terminal block.