AIIM MS58-1996 Standard Recommended Practice for Implementation of Small Computer Systems Interface (SCSI-2) (X3.131-1994) for Scanners《扫描仪应用小型计算机系统接口(SCSI-2) (X3.131-1994)标准推荐规程》.pdf

1、 AIIM PIS58 9Cr U 1032348 0500786 TO8 ASSOCIATION FOR INFORMATION 11 O0 Wayne Avenue Suite 11 O0 Maryland 20910 AlIM MANAGEMENT 301 -587-8202 INTERNATIONAL COPYRIGHT Association for Information Z A7 A a AI2 A SEATING PLANE Pin X Pin Y Pin Z Dimensions 25 34 26 35 so 68 Al A2 A3 A4 A5 A6 A7 A8 AS 0.2

2、3 0,009 . 0.23 0,009 AIO 0,6of0,03 O,024iO,O01 0,6O,O3 0,024I0,OOl AI7 I 0.23 I 0.009 I 0.23 I . 0.009 Figure 6 - 50/68-contact shielded high-density cable connector (This figure corresponds to figure 6 in ANSI X3.131.) 10 Association for Information and Image Management International COPYRIGHT Asso

3、ciation for Information R2 = 124R, 1%; R3-R20= 100S2, 2%. The voltage regulator shown is an adjustable shall be 1,25 V or -DB(P) -ATN -BSY -ACK -RST -MSC -SEL -C/D -REQ - I/O R20 Figure 9 - Termination for singe-ended devices (This figure corresponds to figure 10 in ANSI X3.131.) 17 Association for

4、Information and Image Management International COPYRIGHT Association for Information the other seven data bits shall be released (i.e., not driven) by this SCSI device. The parity bit B(P) may be released or driven to the true state, but shall never be driven to the false state during this phase. Th

5、e signal shall be driven by the initiator, target, or both, as specified in the SELECTION phase and RESE- LECTION phase. If driven, this signal shall be driven only by the active initiator. The signai shall be released; that is, not be driven by any SCSI device. The bias circuitry of the bus termina

6、- tors pulls the signal to the false state. The signal shall be driven by the one SCSI device that wins arbitration. If the signal is driven, it shall be driven only by the active target. I see ANSI X3.131 6.1.3.1 and 6.1.4.2 for a complete description. 4.7.17 Selection time-out delay The minimum ti

7、me that a SCSI device should wait for a BSY response during the SELECTION or RESELECTION phase before starting the time-out procedure. Note that this is only a recommended time period. 4.7.18 Transfer period The minimum time allowed between the leading edges of successive REQ pulses and of successiv

8、e ACK pulses while using synchro- nous data transfers. (See ANSI X3.13 1, clause 6.1.5.2 and 6.6.21 .) 4.8 Fast synchronous transfer option When devices negotiate a synchronous data transfer period of less than 200 ns they are said to be using “fast synchronous data transfers.” (Devices which negoti

9、ate a synchronous data transfer period greater than or equal to 200 ns use timing parameters speci- fied in 4.7.) When a fast synchronous data transfer period is negotiated, those specific times redefined in this section are used; those not redefined remain the same. The minimum synchronous data tra

10、nsfer period is 100 ns. 8.8.1 Fast assertion period This value is the mini- mum time that a target shall assert REQ while using fast synchronous data transfers. Also, the minimum time that an initiator shall assert ACK while using fast synchronous data transfers. 4.8.2 Fast cable skew delay This val

11、ue is the maxi- mum difference in propagation time allowed between any two SCSI bus signals measured between any two SCSI devices while using fast synchronous data trans- fers. 4.8.3 Fast deskew delay This value is the minimum time required for deskew of certain signals while using fast synchronous

12、data transfers. 4.8.4 Fast hold time This value is the minimum time added between the assertion of REQ or ACK and the changing of the data lines to provide hold time in the initiator or target, respectively, while using fast syn- chronous data transfers. 4.8.5 Fast negation period This value is the

13、mini- mum time that a target shail negate REQ while using fast synchronous data transfers. Also, the minimum time that an initiator shall negate ACK while using fast synchronous data transfers. 5 Scanner devices - This clause corresponds to clause 15 of ANSI X3.13 1. - 5.1 Model for scanner devices

14、Scanner devices generate a digital representation of two or three dimensional objects (e.g., a page of text, a photograph, or a piece of art). This is accomplished by sensing the amount of light transmitted from the object and generating the digital data. The digital data can then be sent across the

15、 SCSI bus to an initiator for further processing. There are two types of scanners in use; in one type, the operations and functions of the scanner are fixed; in the other type, the operations and functions are pro- grammable and need to be set up prior to being used for scanning objects. The scanner

16、 device generates the data and transfers it in accordance with the commands received from the initiator. The contents of the data is vendor specific, therefore the initiator and the scanner must know how to use the contents of the data. Scanners generate a digital image of an object in a two dimensi

17、onal plane. The x-axis dimension is along the cross-scan direction which is perpendicular to the - 24 Association for Information and Image Management International COPYRIGHT Association for Information the target disconnects until the resource or data is available, and then re-connects to resume th

18、e operation; a BUSY status is returned. b. c. If the scanner device determines that an error or exception condition has occurred while executing the SCSI command from the initiator, a CHECK CONDI- TION status is returned. A REQUEST SENSE com- mand can then be used to determine additional information

19、 regarding the error or exception condi- tion. 5.2 Commands for scanner devices The commands for scanner devices shall be as shown in table 6. 25 Association for Information and Image Management International COPYRIGHT Association for Information & Imaging ManagementLicensed by Information Handling Services