Simplex G-Link Test Destination Card (TDC) Data Sheet


This Data Sheet describes a test data checker card which is using the HP G-Link as physical medium. This receiver is checking the data sent by  the Test Data Source (TSC) card. It is not recommended to use this card with any other G-Link transmitter. Use the simplex G-Link-S-LINK LDC instead.
This card is using the same hardware as the simplex G-Link-S-LINK LDC, it differs from it in the FPGA configuration.

Data Transfer Rate

The expected parallel data rate is 40 Mhz. This corresponds to 960 Mbaud serial data rate since the G-Link in 20 bit mode sends 24 bit data with each 20 bit data word.  Flow control is not implemented.

Data Pattern

The card expects to receive data in packets which consist of a start of packet control word, 224 data words and an end of packet control word. Fill Frames are transmitted between the packets. Test data is sent on the 16 LSB of the data words. Bits 19-16 contain the odd parity of each four bits of the 16 LSB and used for error detection. E.g. bit 20 is the odd parity of bits 15-12.
Four different data patterns can be selected with the URL1, URL0 return line inputs (see Table 1). The 16 MSB of the S-LINK data output are used for error checking and diagnostic purposes. Table 2 shows the allocation of LD[31..0] bits. The "#" symbol means an active low signal.
LD31 LD30 LD29 LD28 LD[27..24]
CAV# (Control Word) DAV# (Data Word) ERR (G-Link error) FLAG (G-Link Flag) URL[1..0]
LD23 LD22 LD21 LD20 LD[19..16] LD[15..0]
Data Error Parity error Packet length error LD[23..21] is not zero Rx Parity Rx Data
 Table 2: Output Data bits

Operation Modes

4 jumpers can be used to select different operation modes. Operation modes in bold italics MUST be selected on this card.
Jumpers TP[1..4] On Off
TP1 Flag bit mode: Flag bit can be used as an extra dataword. Flag bit is is internally alternated by G-Link for enhanced error detection. 
TP2 20 bit G-Link mode 16 bit G-Link mode
TP3 Link Synchronisation with on-board reference oscillator Link Synchronisation with sync. pulses (Fill Frames)
TP4 Write only erroneous words Write all received words
Table 3: Operation Modes

The following setting must be used when this card is used with the Test Data Source card:
TP1: Off
TP2: On
TP3: On (If this jumper is removed, the TSC must be reset to send sufficient fill frames for the receiver to synchronise.)
TP4: It is up to the user to decide whether it is more convenient to reveive all the data words and trigger on the words in error only (e.g. with a logic analyzer) or receive only the erroneous word (e.g. with an S-LINK destination system).

Led Indicators

Last Updated: 28.06.1999 by Zoltán Meggyesi