Reference Manual

Turbo PMAC/PMAC2 Software Reference
Turbo PMAC Global I-Variables 35
TURBO PMAC GLOBAL I-VARIABLES
General Global Setup I-Variables
I0 Serial Card Number
Range: $0 to $F (0 to 15)
Units: None
Default: $0
I0 controls the Turbo PMAC card number for software addressing purposes on a multi-drop serial
communications cable. If I1 is set to 2 or 3, the Turbo PMAC must be addressed with the @n command,
where n matches the value of I0 on the board, before it will respond. If the Turbo PMAC receives the @n
command, where n does not match I0 on the board, it will stop responding to commands on the serial
port. No two boards on the same serial cable may have the same value of I0.
If the @@ command is sent over the serial port, all boards on the cable will respond to action commands.
However, only the board with I0 set to 0 will respond to the host with handshake characters (no data
responses are permitted in this mode). All boards on the cable will respond to control-character action
commands such as <CTRL-R>, regardless of the current addressing.
Note:
RS-422 serial interfaces must be used on all Turbo PMAC boards for multi-drop
serial communications; this will not work with RS-232 interfaces. If the RS-422
interface is not present as a standard feature on the PMAC2 board, the Option 9L
serial converter module must be purchased. It is possible to use an RS-232
interface on the host computer, connected to the RS-422 ports on the Turbo PMAC
boards.
Typically, multiple Turbo PMAC boards on the same serial cable will share servo and phase clock signals
over the serial port cable for tight synchronization. If the servo and phase clock lines are connected
between multiple Turbo PMACs, only one of the Turbo PMAC boards can be set up to output these
clocks (E40-E43 ON for Turbo PMAC; E1 jumper OFF for Turbo PMAC2). All of the other boards in
the chain must be set up to input these clocks (any of E40-E43 OFF for Turbo PMAC; E1 jumper ON for
Turbo PMAC2).
Note:
Any Turbo PMAC board set up to input these clocks is expecting its Servo and
Phase clock signals externally from a Card 0. If it does not receive these clock
signals, the watchdog timer will immediately shut down the board and the red LED
will light.
If the Turbo PMAC is set to receive external Servo and Phase clock signals for synchronization purposes,
but is not using multi-drop serial communications, I0 does not need to be changed from 0.
To set up a board to communicate as Card 1 to Card 15 on a multi-drop serial cable, first communicate
with the board as Card 0. Set I0 to specify the card number (software address) that the board will have on
the multi-drop cable. Also, set I1 to 2 to enable the serial software addressing. Store these values to the
non-volatile flash memory with the SAVE command. Then turn off power; if the board is to input its
clocks, remove any jumper E40-E43 (Turbo PMAC) or put a jumper on E1 (Turbo PMAC2), connect the
multi-drop cable, and restore power to the system.