Hardware Manual for the PCD2.M5 Series│Document 26/856; Version EN 12│2014-07-24
Saia-Burgess Controls AG
PCD2.H150
Input/output (I/O) modules
6-97
6
6.16
SSI encoder module
PCD2.H150 SSI interface module
I/O modules and I/O terminal blocks may only be plugged in and removed when the
PCD and the ex24 V are disconnected from the power supply.
6.16.1 PCD2.H150, SSI interface module for absolute encoder
Application
The PCD2.H150 module is an interface module for the SSI standard. (SSI =
Synchronous Serial Interface). The SSI standard is used with most absolute
encoders. Details of SSI specifications can be obtained from the STEGMANN
company’s brochure: “SSI-Technical Information”.
The hardware consists of an RS-422 port for the SSI interface and 4 general-purpose
digital outputs. Functionality is provided by an FPGA (field programmable gate array).
Technical data
Resolution:
configurable for 8..29 data bits and 0..2 control bits
Clock frequency:
configurable for 100 kHz, 200 kHz, 300 kHz
and 500 kHz (input filter designed for 500 kHz)
Frequency has to be selected
depending on cable length:
Cable length Frequency
< 50 m max.
500 kHz
< 100 m max. 300 kHz
< 200 m max. 200 kHz
< 400 m max. 100 kHz
Data code:
configurable - Gray or binary
Read mode:
Normal (single read). Ring mode: ‘double read and com
-
pare’ (not all encoders support this function)
Offset position:
An offset can be defined when initializing the PCD2.H150.
The defined offset is always subtracted in the FBs. The
‘Set Zero’ command also uses this offset register.
Execution time:
typically 1.5 ms for reading the SSI value
Cable break detection:
detected with the FB ‘timeout’ (10 ms)
Flags
for cable break, encoder fault or incorrect addressing)
‘fPar_Err’, (if a wring FB parameter is sent)
‘fRing_err’ (if compare error in ‘double read’)
SSI interface
1 input for SSI data
RS-422, electrically isolated
1 output for SSI clock
RS-422, electrically connected,
as the encoder input is normally isolated
Digital outputs
Number of outputs:
Terminal 4 = O12:
Terminal 5 = O13:
Terminal 6 = O14:
Terminal 7 = O15:
4
Speed high
Speed low
Dir + positive direction
Dir - negative