IB(4) — Silicon Graphics
NAME
ib − IEEE 488 interface
SYNOPSIS
device ib0 at mb0 csr 0x020 priority 5 vector ibintr
device ib1 at mb0 csr 0x100 priority 5 vector ibintr
DESCRIPTION
This is the driver for the National Instruments GPIB-796 IEEE 488 bus controller. Talker and Listener functions are provided. The driver may be initialized to provide Controller functions as well. After initialization and startup (eg, with iib(1l)), bytes written to the device file are talked to the corresponding listener, and bytes read from the device file are listened from the corresponding talker. The "End" bit is sent with the last byte of each write request. Read requests return up to the next "End" byte. Writes are synchronous.
From the driver’s perspective, the 488 bus connects up to 8 "nodes" (physical slots), of which its controller is the 0th. The low-order 3 bits of the minor device number are the correspondent’s node number (this is not the same thing as its gpib address). The remaining bits specify which controller if the workstation has more than one.
The driver must be fully initialized before it can be used for file i/o, since it needs a certain amount of "system integrator" information to function. In particular, the driver will function as Controller In Charge if the initialization (see IBIOSETNODE) designates it as System Controller. Startup marks the end of initialization. Initialization and miscellaneous functions are provided via ioctl(2). Some of these functions are available only to the super-user. The codes and structures are defined in the standard include file <sys/ib_ioctl.h>.
ioctl(fd,IBIOGETNODE,struct_sgnode_ptr)
Fills in the struct_sgnode_ptr->node field with the driver’s current idea of the per-node system integrator information for the node (physical slot) number given in the struct_sgnode_ptr->slotno field.
ioctl(fd,IBIOSETNODE,struct_sgnode_ptr)
Changes the driver’s per-node system integrator information for the node number given in the struct_sgnode_ptr->slotno field, according to the struct_sgnode_ptr->node field. Super-user only, and only before startup.
ioctl(fd,IBIOSTART,int_ptr)
Ends initialization and allows normal file i/o to occur if *int_ptr is non0, otherwise just re-enters initialization. Super-user only.
ioctl(fd,IBIOINIT,0)
Initializes (or re-initializes) the driver’s internal data structures. This call should only be made when no other processes are using the driver. Super-user only.
ioctl(fd,IBIOPPC,int_ptr)
Remotely configures the given nodes for parallel polling. If bit i of *int_ptr is 1, node i is configured according to its n_ppr as set by the IBIOSETNODE ioctl. Only nodes with IBN_VALID and IBN_PPC set in the n_flags field are configured. By default, node i uses line i for parallel polling. This call is not interruptible.
ioctl(fd,IBIOPOLL,char_15_ptr)
Fills in the given array with the responses from the last poll; position i is the response from node i. Responses with the 0100 (octal) bit turned on are considered active; other responses are considered inactive and are ignored. If no poll has been done since the previous IBIOPOLL call, return is not until the next poll occurs. The driver performs polls automatically in response to Service Request events: a parallel poll is done first, followed by a serial poll of all matching nodes known to be capable of responding to a parallel poll, plus all nodes known to be incapable of responding to a parallel poll. Parallel poll responses are assumed to be "in-phase," ie, logic 1 when active. This call is effective only if issued from the Controller In Charge side.
ioctl(fd,IBIOSRQ,int_ptr)
Raises Service Request with *int_ptr as poll status. The poll status must have the 0100 (octal) bit turned on. Returns when serial-polled or timeout (currently about 10 seconds). This call is not interruptible.
ioctl(fd,IBIOTAKECTL,0)
Waits for the interface to become Controller In Charge. Super-user only, and only after startup. This cannot take effect until the driver is quiescent. This call is not interruptible.
ioctl(fd,IBIOPASSCTL,int_ptr)
Passes control to the node indicated by *int_ptr. Super-user only, and only after startup. This cannot take effect until the driver is quiescent. This call is not interruptible. This call is effective only if issued from the Controller In Charge side.
ioctl(fd,IBIOCUTOFF,0)
Unaddresses the current talker and listener. This does not interfere with normal driver operation (normally the driver does not unaddress the current talker or listener until another talker or listener is selected; this call unaddresses and forces re-addressing next time). This call is effective only if issued from the Controller In Charge side.
In general iib(1l) is sufficient for dealing with ib driver ioctl’s.
The most efficient blocksize for writes is 1024 bytes. Throughput may reach 110 *1024 bytes per second. The IEEE 488 "compliance" code for this device and driver is approximately
SH1 AH1 C5 T8 L4 SR1 RL0 PP1
FILES
/dev/ib[01][0-7]
SEE ALSO
DIAGNOSTICS
See intro(2).
BUGS
When the interface is not Controller In Charge, the driver has no knowledge of the actual destination when it talks or the actual source when it listens: data from write requests is talked to whatever node happens to be listening when the interface is addressed to talk; listened data is put in an anonymous queue, which is used to satisfy read requests as if it had come from the requested node. In practical terms, this means that when the interface is not Controller In Charge it only talks or listens to the actual Controller In Charge. Due to hardware limitations, killing a program while it’s listening may occasionally scramble subsequent transfers. Due to hardware limitations, the driver may occasionally hang when addressed to listen. Responds to Service Requests only when the file is open. No raw i/o. No asynchronous i/o.
Version 2.3 — July 04, 1985