Impulse 3095 - Manual (Page 10)

© Sealevel Systems, Inc. - 8 - REL-16 User Manual
Output Ports (Reed Relay)
Reed relays provide very high quality, long life, low current (10 Watt maximum),
dry contact switch closures. Reed relays are not suited for high current applications,
and can be destroyed by inductive load switching, where a spark occurs across the
contacts internally. The relays are normally open, and close when energized.
Output Ports (Reed Relay) Pin Assignments (P2)
Port C
Bit
Relay P2 Pin Port D
Bit
Relay P2 Pin
0 K16 2,20 0 K8 10,28
1 K15 3,21 1 K7 11,29
2 K14 4,22 2 K6 12,30
3 K13 5,23 3 K5 13,31
4 K12 6,24 4 K4 14,32
5 K11 7,25 5 K3 15,33
6 K10 8,26 6 K2 16,34
7 K9 9,27 7 K1 17,35
Ground 18,36,37
+ 5 Volts 19
+ 12
Volts
1
Direct Hardware Control
In systems where the user’s program has direct access to the hardware (i.e. DOS) the
table below gives the mapping and functions that the REL-16 provides.
Function
Available
Port Port
Address
Port Type
Base + 0 Unused
Base + 1 Unused
R/W A Base + 2 Output Port
R/W B Base + 3 Output Port
R/W = Read or Write
Relative Addressing vs. Absolute Addressing
The SeaIO API makes a distinction between “absolute” and “relative” addressing
modes. In absolute addressing mode, the Port argument to the API function acts as a
simple byte offset from the base I/O address of the device. For instance, Port #0
refers to the I/O address base + 0; Port #1 refers to the I/O address base + 1.
Relative addressing mode, on the other hand, refers to input and output ports in a
logical fashion. With a Port argument of 0 and an API function meant to output
data, the first (0
th ) output port on the device will be utilized. Likewise, with a Port
argument of 0 and an API function designed to input data, the first (0 th ) input port of
the device will be utilized.
In all addressing modes, port numbers are zero-indexed; that is, the first port is port
#0, the second port is #1, the third #2, and so on.