S800 Documentation

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====== Top level packet tags ======

The top level packet tags are defined as (c code):

<code>
 #define S800_VERSION	          0x0006
 #define S800_PACKET	          0x5800
 #define S800_TRIGGER_PACKET      0x5801
 #define S800_TOF_PACKET          0x5802
 #define S800_TIMESTAMP_PACKET	  0x5803
 #define S800_EVENT_NUMBER_PACKET 0x5804
 #define S800_FP_SCINT_PACKET	  0x5810
 #define S800_FP_IC_PACKET	  0x5820
 #define S800_FP_TIME_PACKET	  0x5830
 #define S800_FP_CRDC_PACKET	  0x5840
 #define S800_II_CRDC_PACKET	  0x5850
 #define S800_TA_PIN_PACKET	  0x5860
 #define S800_II_TRACK_PACKET	  0x5870
 #define S800_II_PPAC_PACKET	  0x5880
 #define S800_OB_SCINT_PACKET	  0x5890
 #define S800_OB_PIN_PACKET	  0x58A0
 #define S800_FP_HODO_PACKET	  0x58B0
 #define S800_VME_ADC_PACKET      0x58C0
 #define S800_GALOTTE_PACKET      0x58D0
</code>


====== Detailed description of each packet tag ======

This section gives details on how to unpack the data associated with each packet tag. The format of the data for each packet tag is frozen as of version 4 of the S800 data format. Further modifications to data associated with a particular detector will result in a new packet tag being defined. Please see the [[S800 data format#Versioning system|versioning system]] section for more details.

===== S800_PACKET =====

This is the outermost packet tag that wraps the entire physics event. Format:

<code>
 S800_VERSION subpackets...
</code>

There are two subpackets that are guaranteed to exist in the data stream. The first subpacket will always be the S800_TIMESTAMP_PACKET. This will be followed by the S800_EVENT_NUMBER_PACKET. Following packets will only be present if there is data to fill them.

===== S800_TIMESTAMP_PACKET =====

A 64 bit timestamp read from a Jtec XLM74 universal logic module. Written as four consecutive words. Format:

<code>
 0xaaaa 0xcccc 0xbbbb 0xdddd 
</code>

where a are bits 15-0, b are bits 31-16, c are bits 47-32 and d are bits 63-48 of the 64 bit timestamp word.

The clock is 10MHz, which means that it will wrap around after approximately 800 years.


===== S800_EVENT_NUMBER_PACKET =====

A 48 bit trigger/event number read from the Weiner VM/CC-USB readout modules. This is incremented each time there is a valid S800 trigger. Format:

<code>
 0xaaaa 0xbbbb 0xcccc 
</code>

where a are bits 15-0, b are bits 31-16 and c are bits 47-32 of the 48 bit trigger/event number word. At a trigger rate of 1.5 kHz this number will wrap around after approximately 6000 years.


===== S800_TRIGGER_PACKET =====

Data read from the Lecroy 2367 ULM module and a Phillips 7186H TDC. One trigger pattern followed by up to four times. Format:

<code>
 0xpppp 0xcttt 0xcttt ...
</code>

where p is the trigger pattern, c is the channel within the TDC and t the data.

^Time data^TDC Channel|
|S800 source|8|
|External1 source|9|
|External2 source|10|
|Secondary source|11|


===== S800_TOF_PACKET =====

Times read from both a Phillips 7186H TDC and an Ortec 566 TAC digitized by a Phillips 7164 ADC. Format:

<code>
 0xcttt ...
</code>

^Time data^TDC channel^TAC channel|
|RF|12| |
|Object Scintillator|13|5|
|XFP Scintillator|14|4|
|Si|15| |

===== S800_SCINT_PACKET =====

Energies and times of the focal plane scintillator, read from a Lecroy 4300B FERA and a Phillips 7186H TDC. A non-zero energy generates an energy and time pair. Format:

<code>
 0xceee 0xcttt ...
</code>

^Detector signal^Channel|
|E1 Up|0|
|E1 Down|1|
|E2 Up|2|
|E2 Down|3|
|E3 Up|4|
|E3 Down|5|


===== S800_FP_IC_PACKET =====

Zero suppressed energies from the ionization chamber, read from a Phillips 7164 ADC. Format:

<code>
 0xceee ...
</code>


===== S800_FP_CRDC_PACKET =====

Data from the two S800 CRDCs in the form of digitized waveform samples read from the Jtec XLM72V ULM, and anode energies and times read from a Phillips 7164 ADC. These packet data contain sub packets. The S800_FP_CRDC_RAW_PACKET contains the waveform samples and the S800_FP_CRDC_ANODE_PACKET contains the energies and times. Each CRDC is read out sequentially and it's data preceded by an id word. Format:

<code>
 0x000i subpackets ...
</code>

where i is the id number (0 or 1).


==== S800_FP_CRDC_RAW_PACKET ====

Sub packet of [[#S800_FP_CRDC_PACKET|S800_FP_CRDC_PACKET]] giving waveform data. Format:

<code>
 0xtttt waveform data ...
</code>

where t is the threshold. The waveform data is written using two consecutive words per sample, to be upacked from the following format (binary representation):

<code>
 word 1: hsss ssss sscc cccc
</code>

<code>
 word 2: 0000 nndd dddd dddd
</code>

where h is the header bit, which should always be 1 for valid CRDC data;

s are the 9 bits of the sample number (maximum number of samples is 512);

c are the 6 bits of the channel number;

n are the 2 bits of the connector number;

d are the 10 bits of data.

==== S800_FP_CRDC_ANODE_PACKET ====

Sub packet of [[#S800_FP_CRDC_PACKET|S800_FP_CRDC_PACKET]] giving energies and times of the CRDCs. Format:

<code>
 0xeeee 0xtttt
</code>


===== S800_FP_HODO_PACKET =====

Up to 32 Hodoscope energies read from Phillips 7164 ADCs, read in sparse mode, hit patterns read from a LeCroy 4448 Coincidence register, and a time value read from an Ortec 566 TAC via a Phillips 7164 ADC. The type of data to extract is determined from the first word of the packet, the id word. The first 16 energies are associated with id = 0, the second 16 with id = 1 and the hit patterns and time with id = 2. Format:

<code>
 (id = 0,1) 0x000i 0xceee ...
</code>

<code>
 (id = 2) 0x000i 0xaaaa 0xbbbb 0xtttt
</code>

where i is the id, a is the coincidence register A for the first 16 channels, b the register for the second 16 channels and t the TAC time.

===== S800_II_TRACK_PACKET =====

Data from the intermediate image tracking PPAC read from a Jtec XLM72V universal logic module in the form of waveform samples. The S800_II_TRACK_PACKET contains no data and is solely a wrapper for the S800_II_TRACK_RAW_PACKET sub packet.


==== S800_II_TRACK_RAW_PACKET ====

Sub packet of [[#S800_II_TRACK_PACKET|S800_II_TRACK_PACKET]] giving waveform data. Format:

<code>
 0xtttt waveform data ...
</code>

where t is the threshold. The waveform data is written using two consecutive words per sample, to be upacked from the following format (binary representation):

<code>
 word 1: hsss ssss sscc cccc
</code>

<code>
 word 2: 0000 nndd dddd dddd
</code>

where h is the header bit, which should always be 1 for valid PPAC data;

s are the 9 bits of the sample number (maximum number of samples is 512);

c are the 6 bits of the channel number;

n are the 2 bits of the connector number;

d are the 10 bits of data.


===== S800_OB_PIN_PACKET =====

Energy from the object box PIN detector, read out from a Phillips 7164 ADC. Format:

<code>
 0xceee
</code>



===== S800_VME_ADC_PACKET =====

Mesytec 32 channel ADC installed in the main VME crate. Conversion is up to 13 bits.

<code>
 0x000i data...
</code>

where i is the id, and four id groups are in the data stream. Information from channels 0-7 is in id 0, 8-15 in id 1, 16-23 in id 2 and 24-32 in id 3. Not all channels may be present. By checking the length word before each packet tag, and unpacking the data word, the non-zero channels can be extracted. The data word format:

<code>
 ccce eeee eeee eeee
</code>

where c is the channel within this id (referred to as read_channel). The true adc channel number can be obtained by calculating (id * 8)+read_channel. e is the energy (11-13 bits dependent upon adc setting).

===== S800_GALOTTE_PACKET =====

Galotte time, up, down, left and right times from the Galotte MCP detector installed in the Object Box. Format:

<code>
 0xcttt
</code>

where c is the channel number (starting from zero and incrementing in the order given above) and t the time data.
S800 Documentation

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