116 -- Safety System Reader

Description

The CARESS Accelerator Division safety system is supposed to repeatedly broadcast its current state (via RS-232) to a special 116 card. The 116 card buffer up the following information, which we can find:

1. One word containing the status (16 bits) of every 'AART', the basic safety system unit. Each bit is (basically) the status of one microswitch (or whatever).
2. A status-of-status bit for every AART, contained in a whole word. This bit is currently not defined.
3. A word for each 'group' of AARTS, which increments every time CARESS sends a new 'group' full of data. There are 32 AARTS in a group.

The database mapping is to have one device for each AART. The 'group' and AART number are baked into the SSDN. We currently believe that there is need for only a few such devices.

The alternative database mappings which we are not implementing at this time are:

1. One device per bit
2. An array device (either 1/group, or 1 for the whole thing)

It would not be difficult to implement these alternative mappings if they become desirable.

SSDN:

Where GGGGG is the CARESS group number and AAAAAAA is the AART number.

Currently we only support the reading property, which returns either 1 or 2 words, depending upon what you requested of 'DPREQ'.

	WORD 0:  AART DATA   READ BY CAMAC F(0)A(2)
	WORD 1:  S-O-S BIT   READ BY CAMAC F(0)A(3)  (OPTIONAL)

	THE S-O-S BIT APPEARS IN THE HIGH ORDER BIT OF WORD 1.

The 'Frequency Time Descriptor', or the data return period, which you specify in the 'DPREQ' call should approximately match the CARESS to 116 card update period. The front end checks the F(0)A(1) data refresh counter at the same rate as your data return period. The front end will return stale data for only a few return periods, after which it returns an error status until more data appears.