Bostjan JERKO wrote:
>
> Hello !
>
> I have UMAX 1220s scanner connected to IOI 4203A SCSI card. Since scanner has DB25
>connector and on SCSI
> card there is only HD 50 connector. I got connector from DB25 to Centronics and then
>a gender changer from Centronics
> to HD 50.. The problem is if I start program that came with the SCSI card and
>nothing is connected to the port it works fine.
> After connecting the scanner to the card the program stops while starting. This
>happens in DOS.
> I tried the same under Linux and if the port is empty Linux recognises SCSI card,
>but if I connect scanner to the port
> it stops while "Reseting SCSI bus ".
>
> Any ideas what might be wrong ?
>
> B.
o I had a lot of problems hooking up a UMAX Astra 1220S scanner to my
Mylex SCSI card. I assumed "SCSI scanner" meant SCSI. In truth, to
a hardware manufacturer "SCSI" means any parallel interface that
isn't some variation on the PC parallel printer port. Don't even
get me started on Apple's decision to use a DB-25 connector for
their SCSI.
(from the SCSI FAQ: "Macintosh Plus SCSI Connector Pinouts. Note
that this connector is NON COMPLIANT WITH ANY SCSI STANDARD! The
grounding is insufficient and does not allow for proper twisted-
pair transmission line implementation. It is recommended that a
short adapter cable be used to convert to the more common
Centronics style 50 pin connection rather than extend the 25 pin
connection any further than necessary.")
o Or, for those who remember, IBM's decision on the original PC to use
a DB-25 for the parallel printer port, when, at the time the
standard was DB-25 for +/- 3-25 volt serial and Amphenol 36 pin
(Centronics) for +0-5 volt parallel. Anyone who designs a product
with a non-standard connector, especially when a standard exists and
the non-standard connector is standard FOR SOMETHING ELSE deserves
to be shot. Okay, enough ranting from me.
o The good news is, given the right cabling, the scanner works. The
bad news is that there are at least two, if not more, "standards"
for converting DB-25 to HD-50. I didn't know this, bought a DB-25
to HD-50 cable at a computer store, and not only didn't it work but
it nearly fried the scanner in the process.
o Here is some documentation I assembled from various sources while
debugging the problem. "MINI-MICRO" is the HD-50 connector.
Unfortunately, I don't remember whether the "DB-25 MAC" or the "DB-
25 Future" pinouts are correct. Measure what you have with the DB-
25 -> Centronics -> HD-50, and go with the other one.
o Hope this helps. In any case, it's the sum total of my knowledge
on the subject.
MINI-MICRO
______________________
| _________________ |
| 1\ - - - - - - - /25 |
| 26\- - - - - - -/50 |
| ------------- |
----------------------
"SCSI-2" male
DB-25P (male)
_____________________________
1\ o o o o o o o o o o o o o /13
14\ o o o o o o o o o o o o /25
------------------------
View from pins of connector.
--------- ---------
| SCSI | | MINI |
| SIGNAL| | MICRO | DB-25 DB-25
--------- --------- MAC Future
GND 1
GND 2
GND 3
GND 4
GND 5
GND 6
GND 7
GND 8
GND 9
GND 10
GND 11
RSR 12
OPEN 13
RSR 14
GND 15
GND 16
GND 17
GND 18
GND 19
GND 20
GND 21
GND 22
GND 23
GND 24
GND 25
-DB(0) 26 8 14
-DB(1) 27 21 2
-DB(2) 28 22 15
-DB(3) 29 10 3
-DB(4) 30 23 16
-DB(5) 31 11 4
-DB(6) 32 12 17
-DB(7) 33 13 5
-DB(P) 34 20 18
GND 35
GND 36
RSR 37
TERMPWR 38
RSR 39
GND 40
-ATN 41 17 20
GND 42
BSY 43 6 23
-ACK 44 5 22
-RST 45 4 10
-MSG 46 2 21
-SEL 47 19 7
-C/D 48 15 11
-REQ 49 1 24
-I/O 50 3 12
--
MARK
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