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

 #define S800_VERSION	        0x0004
 #define S800_PACKET	        0x5800
 #define S800_TRIGGER_PACKET	0x5801
 #define S800_TOF_PACKET		0x5802
 #define S800_TIMESTAMP_PACKET	0x5803
 #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

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 versioning system section for more details.

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

 0xpppp 0xcttt 0xcttt ...

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

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

 0xcttt ...

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:

 0xceee 0xcttt ...

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

 0xceee ...

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:

 0x000i subpackets ...

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

Sub packet of S800_FP_CRDC_PACKET giving waveform data. Format:

 0xtttt waveform data ...

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):

 word 1: hsss ssss sscc cccc

 word 2: 0000 nndd dddd dddd

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.

Sub packet of S800_FP_CRDC_PACKET giving energies and times of the CRDCs. Format:

 0xeeee 0xtttt

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:

 (id = 0,1) 0x000i 0xceee ...

 (id = 2) 0x000i 0xaaaa 0xbbbb 0xtttt

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.

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.

Sub packet of S800_II_TRACK_PACKET giving waveform data. Format:

 0xtttt waveform data ...

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):

 word 1: hsss ssss sscc cccc

 word 2: 0000 nndd dddd dddd

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.

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

 0xceee

A 48 bit timestamp read from a Jtec XLM74 universal logic module. Written as three consecutive words. Format:

 0xhhhh 0xmmmm 0xllll

where h are bits 47-32, m are bits 31-16 and l bits 15-0 of the 48 bit timestamp word.