Operate switch

Description

This function obtains, and optionally sets, the state of a switch. It allows explicit access to the individual switches making up a sub-unit, in types where their operation is normally handled automatically by the driver. The main purpose of this is in implementing fault diagnostic programs for such types; it can also be used where normal automated behaviour does not suit an application.

Prototype

DWORD PIPLX_OpSwitch(SESSION session, DWORD CardNum, DWORD OutSub, DWORD SwitchFunc, DWORD SegNum, DWORD SwitchNum, DWORD SubSwitch, DWORD SwitchAction, BOOL *State);

Parameters:

Session - The session variable obtained from the PICMLX_Connect call

CardNum - card number

OutSub - sub-unit number

SwitchFunc - code indicating the functional group of the switch, see below

SegNum - the segment location of the switch

SwitchNum - the number of the switch in its functional group (unity-based)

SubSwitch - the number of the subswitch to operate (unity-based)

SwitchAction - code indicating the action to be performed, see below

State - pointer to variable to receive the state of the switch (after performing any action)

Returns:

Zero for success, or non-zero error code.

Applicable sub-unit types

This function is only usable with matrix sub-units having auto-isolation and/or auto-loopthru features. For further information see: segmented matrix, unsegmented matrix.

SwitchFunc value

A value indicating the functional group of the switch to be accessed.

SegNum value

The segment location of the switch. The numbers and sizes of segments on each matrix axis can be obtained using PIPLX_SubAttribute.

In an unsegmented matrix, use SegNum = 1.

In a segmented matrix, segment numbers for crosspoint and isolation switches are determined logically.

SwitchNum value

The number of the switch in its functional group (unity-based).

For channel (crosspoint) switches, the switch number can be either:

• if SegNum is zero, the global channel number of the switch (see output bit number)

• if SegNum is non-zero, the segment-local number of the switch, calculated in a similar way to the above

SubSwitch value

The number of the subswitch to operate (unity-based). This parameter caters for a situation in which a logical channel, isolation or loopthru switch is served by more than one physical relay (as for example when 2-pole operation is implemented using independently-driven single-pole relays).

The numbers of subswitches for each functional group can be obtained using PIPLX_SubAttribute.

SwitchAction value

A code indicating the action to be performed.

Loopthru switches

Loopthru switches are initialised by the driver to a closed state, which may mean that they are either energised or de-energised depending upon their type. In normal automated operation loopthru switches open when any crosspoint on their associated line is closed. Actions SW_ACT_CLOSE and SW_ACT_OPEN close or open loopthru switch contacts as their names imply.

Operational considerations

This function can be used to alter a pre-existing switch state in a sub-unit, set up by fuctions such as PIPLX_OpBit or PIPLX_WriteSub. However once the state of any switch is changed by PIL_OpSwitch the logical state of the sub-unit is considered to have been destroyed. This condition is flagged in the result of PIPLX_SubStatus (bit STAT_CORRUPTED). Subsequent attempts to operate it using 'ordinary' switch functions such as PIPLX_OpBit, PIPLX_ViewBit etc. will fail (result ER_STATE_CORRUPT). Normal operation can be restored by clearing the sub-unit using PIPLX_ClearSub, PIPLX_ClearCard or PIPLX_ClearAll.