1.3 The SR470 Rear Panel
1 – 23
1.3.8.3 RS-232
The RS-232 interface connector is a standard 9 pin, type D, female
connector configured as a DCE (transmit on pin 3, receive on pin
2). The factory default communication parameters are set to: 8 Data
bits, 1 Stop bit, No Parity, No Hardware Flow Control. All of these
parameters are fixed. The interface is enabled or disabled, and the
baud rate is set from the front panel. Please see
§
1.2.6.1 for more
information.
Figure 1.5: Grounding the shield of the shutter cable.
1.3.9
Shutter grounding considerations
For reliable operation of a shutter head connected to the SR470 it
is essential that the shield of the cable to the shutter is properly
grounded.
The grounding scheme for the shutter cable is shown in Fig. 1.5.
The cable connects a rear-panel output to an external shutter head.
Inside the shutter head, there is an electrical connection between its
chassis (case) and the shield of the cable. If the chassis of the shutter
head is electrically connected to earth ground, for example by way
of attachment to a grounded optical table, then the shield will be
grounded as well. The SR470 can internally connect the cable shield
to ground or leave it floating, as selected by an internal jumper for
each channel. The factory default setting is to ground the shield for
each of the four shutter channels.
If a shutter head is properly grounded and thereby providing a suit-
able ground to the cable shield, it may be desirable to remove the
shield-ground connection for the shutter cable inside the SR470 .
Figure 1.6: Shutter cable ground selection header. Part (a) shows
the cable shield grounded at the SR470 with the jumper over the
two pins marked “GROUND” and part (b) shows the cable ground
floating, where the jumper sits over the two pins marked “FLOAT.”
SR470 Shutter Controller
