Specifications

Port Protocols and POSjet
®
1500 Programmer's Guide
Connection Specifics
Page 256 Rev N Nov-10
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.
Figure 35 Parallel Port ACK Timing Options
Legend
Time Interval
Minimum
Maximum
t1
DATA Setup to STB
0.5 uS
t2
STB Width
0.5 uS
500 uS
t3
DATA Hold after STB
0.5 uS
t4
BUSY Delay after STB
0
0.5 uS
t5
ACK Pulse Width
2.5 uS
Table 68 Parallel-port Timing
Note: Altered STB timing to take data on the falling edge of STB can be generated as a factory option.
Data
STB
BUSY
ACK
ACK
ACK
ACK-while-BUSY
ACK-in-BUSY
ACK-after-BUSY
t1
t2
t3
t4
t5