Sensoray 425 - Manual (Page 14)

Sensoray Model 425 Instruction Manual Page 12
Relay Interface
Register
I/O Channel
Local
Data
Bus
One of 48 Digital I/O Channels
O.C.
Relay Access Ports
The 48 relay channels are accessed through three
bidirectional I/O ports. Each port accesses 16
channels simultaneously:
Reading from a Relay port returns the physical state
of the channels associated with that port. Writing to a
Relay port programs the associated relay channel
output registers.
Note: the value read from a relay channel may not be
the same as the value stored in that channels output
register. Specifically, the values will differ if an
output register is programmed to 0 and an external
sink pulls the corresponding channel down to 0V.
Configuring I/O Type
Each channel may be independently configured as
either an input or output. To configure a channel as
an input, zero the associated channel register.
Relay 0-15 port (base + 24, read/write)
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
R15 R14 R13 R12 R11 R10 R9 R8 R7 R6 R5 R4 R3 R2 R1 R0
Relay 31-16 port (base + 26, read/write)
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
R31 R30 R29 R28 R27 R26 R25 R24 R23 R22 R21 R20 R19 R18 R17 R16
Relay 47-32 port (base + 28, read/write)
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
R47 R46 R45 R44 R43 R42 R41 R40 R39 R38 R37 R36 R35 R34 R33 R32
Connections
All electrical connections are made through 50-pin
connectors P3 and P1. On each of these connectors,
one pin is assigned to each active-low I/O channel.
All even pins are connected to ISAbus five volt return.
In addition, pin 49 may be used to supply limited five
volt power (<100mA) to an external relay rack.
Pin P1 P3
1 CH23 CH47
3 CH22 CH46
5 CH21 CH45
7 CH20 CH44
9 CH19 CH43
11 CH18 CH42
13 CH17 CH41
15 CH16 CH40
17 CH15 CH39
19 CH14 CH38
21 CH13 CH37
23 CH12 CH36
25 CH11 CH35
27 CH10 CH34
29 CH9 CH33
31 CH8 CH32
33 CH7 CH31
35 CH6 CH30
37 CH5 CH29
39 CH4 CH28
41 CH3 CH27
43 CH2 CH26
45 CH1 CH25
47 CH0 CH24
49 +5V +5V
Even GND GND
The 425 board provides 48 high-current digital
I/O channels designed for direct interface to
industry standard relay racks.
As shown in the diagram to the right, each relay
channel is physically structured as a write-only
register followed by an open-collector buffer
(with 10Kohm pullup), which in turn is looped
back to the local data bus by a 3-state buffer.
Channel data is active-high on the local bus side,
and active-low on the I/O channel side.