Table 68 Parallel-Port Timing; Figure 35 Parallel Port Ack Timing Options - TransAct POSjet 1500 Programmer's Manual

Port Protocols and
Connection Specifics
Some systems may wish to change the details of how the strobe, busy, and acknowledged signals interact. The
parallel-port option features define how the strobe, busy, and acknowledged signals operate. In normal mode, the
printer follows the standard (Centronics) parallel-port conventions. With Options 1 and 3, the acknowledged and
busy signals change simultaneously, which is sometimes referred to as ack-after-busy. Options 2 and 3 force busy
high, on the rising edge of the strobe, which is sometimes referred to as busy-while-strobe timing. In all cases, the
data is latched on the rising edge of the strobe. In most cases, the normal timing mode gives the best results.
Data
STB
BUSY
ACK
ACK
ACK
Legend
t1 DATA Setup to STB
t2 STB Width
t3 DATA Hold after STB
t4 BUSY Delay after STB
t5 ACK Pulse Width
Note: Altered STB timing to take data on the falling edge of STB can be generated as a factory option.
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POSjet 1500
t1
t3
t2
t4
ACK-while-BUSY
ACK-in-BUSY
ACK-after-BUSY

Figure 35 Parallel Port ACK Timing Options

Time Interval

Table 68 Parallel-port Timing

Rev M
t5
Minimum
0.5 uS
0.5 uS 500 uS
0.5 uS
0 0.5 uS
2.5 uS
Programmer' s Guide
Maximum
Nov-07