Device Descriptions

Device descriptions (type *DEVD) are objects that the system uses to store information about a peripheral device such as a display station, a printer, or a tape drive. This section will concentrate on the display stations and the printers.

Naming Device Descriptions

Device descriptions must have reasonable names just as user profiles do. If you use IBM's naming system (which is enforced when you use automatic configuration), you end up with entirely meaningless device description names such as DSP17 or PRT010203.

If you see a message at the system console that informs you that someone has attempted to sign on at display station DSP23 using an invalid user profile name, you probably will not know where DSP23 is. It could be right next to you or at the other end of the building.

The following is a more meaningful naming system for display stations and printers (and even for other device descriptions). The system uses three letters to abbreviate the location of the device, plus DSP or PRT, plus two digits for sequencing. The number 01 is always reserved for the department's manager.

Location abbreviations are entirely up to you. For example, you could use ACG for Accounting and INV for Inventory. The main printer in Accounting would then be ACGPRT01 and the Accounting manager's display station is ACGDSP01. Table 13.4 shows some suggestions for your device description names.

Table 13.4: Suggested Device Description Names.

Location	Description
ACG	Accounting
ASY	Final Assembly
CNF	Conference Room
CSV	Customer Service
ENG	Engineering
FIN	Finance
HUM	Human Resources
INV	Inventory Control
LAB	Laboratory
LBY	Lobby (reception area)
MGT	Management
MKT	Marketing
MIS	Information systems
OFC	General Office
OPS	Operations
PRD	Production Control
PUR	Purchasing
QLT	Quality Control
RCV	Receiving
SAL	Sales
SHM	Sheet Metal
SHP	Shipping
SYS	System
WHS	Warehouse

A few device types are described in Table 13.5.

Table 13.5: Suggested Device Type Names.

Device	Description
DKT	Diskette
DSP	Display
CNF	Conference Room
TAP	Tape

You can name your system console SYSDSP01 and your system printer SYSPRT01. The main tape drive can be SYSTAP01.

Maintaining Device Descriptions

You can create, change, delete, and display device descriptions at any time. Any changes you make become effective immediately. The system doesn't require you to IPL it or perform any other major chore for your changes to be accepted. If, at any time of the day, you receive a call from the Marketing department for an additional display station, you can plug it in, turn it on, connect it to the system, and begin using it.

If system value QAUTOCFG is set to ‘1,’ the system automatically takes care of the configuration of your local device descriptions, because they communicate with the system by regular cables and do not require telephone lines. In this case, you don't have to worry about creating the device descriptions. You only connect the new device, turn it on, wait less than a minute, and the system configures it for you, makes it ready, and presents the sign-on display. If the device is a printer, it will be ready to print.

Again, automatic configuration creates meaningless names for the devices. The first display station is named DSP01; the second station, DSP02; and so on. There also is a more subtle problem with automatic configuration: If you swap two different devices (for example a 5251 model 11 display station and a 3196 display station), the system sometimes deletes the old display stations and creates new ones because it senses that the models don't match anymore. This changes the old names of the two display stations. Instead of being DSP12 and DSP15, for example, they may become DSP38 and DSP39.

Tip 

You are better off disengaging automatic configuration as soon as you become familiar with the commands used to configure devices manually. These commands are the Create Device Description commands (CRTDEVXXX), where xxx is DSP for display stations and PRT for printers. Other values are possible for xxx, but they are beyond the scope of this book.

You can change many (but not all) of the settings of a device description once it is created by using the corresponding Change Device Description (CHGDEV XXX) command. Again, xxx can be replaced by DSP or PRT. You can also display a device description using the DSPDEVD command or delete the device descriptions using the Delete Device Description (DLTDEVD) command. Neither has xxx variations.

Tip 

You can also rename a device description using the Rename Object (RNMOBJ) command. The device description's message queue is automatically renamed. This provides a way to change the meaningless names given to device descriptions by automatic configuration. Be sure to vary off the device before running RNMOBJ, and to vary it back on afterwards.

For example, if automatic configuration created DSP42, and you want to name it OFCDSP03, run the following command:

      RNMOBJ OBJ(DSP42) OBJTYPE(*DEVD) NEWNAME(OFCDSP03) 

Taking charge of this maintenance is not as bad as it seems. A Work with Device Descriptions (WRKDEVD) command lists all available device descriptions. You can perform any of the device description commands from here, including making a copy using option 3. This copy function is great when you have just configured a new device description and you realize that now you must configure another one that is almost identical.

When you create a new local display device description, pay attention to the following parameters:

• TYPE and MODEL, which define the type of machine (for example, a 3477 model FC)

• CTL, PORT, and SWTSET, which indicate where the new display is connected. CTL is the name of the workstation controller, which is usually CTL01. PORT is a number from 0 to 7, and SWTSET is a number from 0 to 6.

• OUTQ and PRTDEV name the default output queue and printer for whatever print jobs are requested from this display.

• AUT tells the system what authority to give the public. Unless you have special security requirements, use a value of *CHANGE so that anyone can use the new display station.

Printers are somewhat different. They do not have OUTQ and PRTDEV parameters, but they have a MSGQ parameter, which names the message queue that receives the messages the system issues when something goes wrong with the printer (such as running out of paper or having a ribbon jam). You need to decide where you want to send these messages. Here are three suggestions:

• Use QSYSOPR, which allows you to have a centralized message queue where you can see all the messages related to printers. Possible disadvantages are that QSYSOPR may be overly busy already without the additional burden of printer messages, and that the system operator might not be near the printer to correct the problem.

• Use one message queue (other than QSYSOPR) for all printers. Doing this relieves QSYSOPR from that burden. Because any user with enough authority can display messages from the message queue, anyone can take corrective action (especially someone near the printer). A disadvantage of this scheme is that it provides little security. By replying to inquiry messages in this message queue, anyone authorized to do so would indirectly control all printers.

• Create a separate message queue for each printer. Separate message queues give the best possible control, and it is not as bad as it sounds, especially if you name the message queue after the printer it controls. If the Receiving department's printer is called RCVPRT01, create a message queue called RCVPRT01 and make it the message queue for the printer. When you need to display messages for RCVPRT01, you will know what message queue to display.

Listing Device Descriptions

Often, you will need to obtain a list of device descriptions. You can do so in three different ways:

• Run the Display Object Description (DSPOBJD) command and specify OBJ(QSYS/*ALL) OBJTYPE(*DEVD). You can direct the output to the display (by default) or to the printer, by specifying OUTPUT(*PRINT). The main problem with DSPOBJD is that it generates a list that shows only the device description names and text descriptions. It doesn't show any of their configuration settings.

• Run the Print Device Address (PRTDEVADR) command. This command produces a printed grid that lists all device descriptions attached to a particular local workstation controller. The command only has one parameter, CTL, where you must name the workstation controller you need to see. Supply a value like CTL01.

• Run the Work with Configuration Status (WRKCFGSTS) command, specifying CFGTYPE(*DEVD) CFGD(*ALL). Like the DSPOBJD command, you can direct the output to the display or to the printer by entering * or *PRINT in the OUTPUT parameter.

None of these commands gives you much information about the actual configuration of the devices. i5/OS has no built-in commands that give you this information.

However, armed with a list of device descriptions (like that produced by the first or third method), you can run the DSPDEVD command individually for each device. Here is a shortcut you can take:

1. Run the WRKDEVD command, and specify DEVD(*ALL). This command does not allow output to a printer, but that doesn't matter.

2. Key in an option 5 (display) next to each device description listed, rolling through all the pages without pressing Enter.

3. Move the cursor to the command line and type OUTPUT(*PRINT). Then press Enter. The WRKDEVD command then processes all your option 5 requests. Option 5 runs the DSPDEVD command, which accepts OUTPUT(*PRINT) as a parameter. Thus, OUTPUT(*PRINT) is appended to all option 5 requests, which results in a multiple execution of DSPDEVD to print.