SeaLevel LATCH-16 User manual

LATCH-16™
PART # 3097
USER MANUAL
Sections:
Introduction
1. Installation
2. Address Selection
3. Technical Description
4. Software
5. Warranty
Figures:
1. Address Selection Table
2. Addressing Example
3. Bit, Relay And Connector Positions
4. Silk-Screen
5. Schematic
Sealevel Systems Incorporated
P.O. Box 830
155 Technology Place
Liberty, SC 29657 USA
[phone] FAX: [phone]
© Copyright 1994 Sealevel Systems Incorporated

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Sealevel Systems Latch-16 Page 1
Introduction
Latching relays retain their state until they are changed by
the user. Power conditions do not ef
fect the latching
relays; therefore, the PC can be powered up or down
without altering the state of the latch. Latching Relays
have two coils as compared to normal relays, with one
coil. The two coils are labeled “set” and “reset”. When
either “set” or
“reset” coil is energized, the relay switches
to that state and remains there until the opposite coil is
pulsed. This allows “non-volatility” in the relay circuit.
The SEALEVEL LATCH-16 provides two 8-
bit
latching relay output ports. This allows the us
er to set the
LATCH-
16 to a desired state, which is unaffected by
power loss or interruption. The 16 relays remain in the
desired state regardless of the power up / down condition
of the PC. Software examples are included to help
minimize development time.

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Sealevel Systems Latch-16 Page 2
SECTION 1. Installation
Be sure to set the Address and Jumper Options Before Installation.
The LATCH-16 can be installed in any of the PC expansion slots, except J8 on the original
IBM "XT" and Portable. Remove the PC case, remove the blank metal slot cover, and insert
the board. Replace the screw, replace the case, and the installation is complete.
SECTION 2. Address Selection
The LATCH-16 relay output board occupies a total of four consecutive I/O locations. A dip
switch is used to set the base address for these locations. Be careful when selecting the
base address as some selections conflict with existing PC ports. The following table shows
several examples that usually do not cause a conflict.
Note that address line A9 is always a "1".
Address Binary Switch Setting
Hex A9 A8 A0 1234567
300-303 11000000XX Off Cn On On On On On
304-307 11000001XX Off Cn On On On On Off
310-313 11000100XX Off On On On Off On On
314-317 11000101XX Off On On On Off On Off
320-323 11001000XX Off On On On Off On On
3A0-3A3 11101000XX Off Off On Off On On On
Figure 1
Address Selection Table
The following table shows the correlation between the dip switch setting and the address bits
used to determine the base address. Assume 300 Hex to 303 Hex is the desired base
address. 300 Hex=11 0000 0X in Binary.
Switch Position Address Line Binary Switch Setting
N/A A9 1Always a 1
1A8 1OFF
2A7 0ON
3A6 0ON
4A5 0ON
5A4 0ON
6A3 0ON
7A2 0ON
Figure 2
Addressing Example
NOTE: Setting the switch "On" or "Closed" corresponds to a "0" in the address, while leaving
it "Off" or "Open" corresponds to a "1".
Port Enable / Disable
The LATCH-16 can be enabled or disabled with switch position 8 on the dipswitch. The port
is enabled with the switch "On" or "Closed" and disabled when "Off" or "Open"

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Sealevel Systems Latch-16 Page 3
SECTION 3. Technical Description
The LATCH-16 provides two eight bit latched relay output ports. Latched Relays maintain
their set or reset condition until set or reset again, regardless of power conditions. This allows
the user to set the LATCH-16 relays in a required state and power down the computer. When
a change is required, the user can simply set or reset the relay(s) again.
Note: The terms “set” and “reset” are used to define the state of the relay. Set means that the
relay “S” coil has been energized, and the relay contacts are closed. Reset means that the
relay “R” coil has been energized, and the contacts are open.
The Latch-16 is easily programmed as simple Port I/0. To set a relay, the corresponding bit in
Base+0 (or Base+2) must be written as a “0”. To reset a relay, the corresponding bit in
Base+1 (or Base+3) must be written as a “0”. Writing to any of these registers causes a 6
mS. (Millisecond) pulse generator to energize the relay coil. This particular hardware
approach was chosen to keep the controlling software from having to use timing routines and
perform tedious I/O operations.
Note: While setting or resetting individual bits requires only one I/O write, writing
a byte of data to the port requires writing both the set and reset register. This
is because only the “0” bits in the byte cause a set or reset operation.
Therefore, to write a byte (55 Hex) to Port A, first write a 55H to Base+0 and
write the complement (AA Hex) to Base+1.
Output Functions: Input Functions:
Base+0 Set relays on Port A (Relays K9-K16) Read status of relays K9-K16.
Base+1 Reset relays on Port A (Relays K9-K16) Read status of pulse generator (Port A).
Base+2 Set relays on Port B (Relays K1-K8) Read status of relays K1-K8.
Base+3 Reset relays on Port B (Relays K1-K8) Read status of pulse generator (Port B).
Again, writing to these registers causes a 6 millisecond (ms) pulse to be applied to the relay
coil. You must avoid successive writes as this 6 ms pulse is necessary to energize the relay.
By reading the registers at Base+1 and Base+3 you can determine if a write is in process
and wait until it is finished before initiating another cycle. The status of the relays may be
read back from Base+0 (K9-16) and Base+2 (K1-K8). Please note that when reading the
status of the relays, a set bit (1) corresponds to an Open relay and a clear bit (0) corresponds
to a Closed relay.
Read Operations
Base+0 An I/O read to Base+0 will return the status of the relays K9-K16. Reading a
zero (0) indicates that the relay is closed. (Port A see Figure 3 for actual
Relay / Port-bit locations)
Base+1 An I/O read to Base+1 will return a 0 in bit position D0 if a write to Base+0 is in
progress (Set A). An I/O read to Base+1 will return a 0 in bit position D1 if a write
to Base+1 is in progress (Reset A).
Base+2 An I/O read to Base+2 will return the status of the relays K1-K8 . Reading a zero
(0) indicates that the relay is closed. (Port B see Figure 3 for actual Relay /
Port-bit locations)
Base+3An I/O read to Base+3 will return a 0 in bit position D0 if a write to Base+2 is in
progress (Set B). An I/O read to Base+3 will return a 0 in bit position D1 if a write
to Base+3 is in progress (Reset B).

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Sealevel Systems Latch-16 Page 4
Software Installation
For Windows Users
Choose Install Software at the beginning of the CD and select the Digital I/O
software drivers and install SeaIO.

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Sealevel Systems Latch-16 Page 5
Port Bit Relay K# DB-37 Pin #
Port A
D0 K13 2,20
D1 K14 3,21
D2 K15 4,22
D3 K16 5,23
D4 K9 6,24
D5 K10 7,25
D6 K11 8,26
D7 K12 9,27
Port B
D0 K5 10,28
D1 K6 11,29
D2 K7 12,30
D3 K8 13,31
D4 K1 14,32
D5 K2 15,33
D6 K3 16,34
D7 K4 17,35
Power and Ground Locations
Ground 18,36,37
+ 5 Volts 19
+ 12 Volts 1
Figure 3
Bit, Relay and Connector Pin Positions
SECTION 4. Specifications
Environmental
Specification Operating Storage
Temperature range 0 -50 Degrees C
32 -122 Degrees F -20 -70 Degrees C -40 -100 Degrees F
Humidity Range 0-90% R.H.
Non-Condensing 0-90% R.H. Non-Condensing
Performance
MTBF > 150,000 Hours
MTTR < .25 Hours
Turnaround For Repair -5 Working Days
Manufacturing
•IPC 610-A Class-III standards adhered to with a 0.1 visual A.Q.L. and 100% Functional
Testing.
•Boards are built to U.L. 94V0 rating and are 100% Electrically tested. Boards are solder
mask over bare copper or solder mask over tin nickel.
Power
Supply Line +5

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Sealevel Systems Latch-16 Page 6
Rating (mA) 210 mA
SECTION 5. Warranty
Sealevel Systems, Inc. provides a lifetime warranty for this product. Should this
product fail to be in good working order at any time during this period, Sealevel
Systems will, at it's option, replace or repair it at no additional charge except as set
forth in the following terms. This warranty does not apply to products damaged by
misuse, modifications, accident or disaster.
Sealevel Systems assumes no liability for any damages, lost profits, lost savings or
any other incidental or consequential damage resulting from the use, misuse of, or
inability to use this product. Sealevel Systems will not be liable for any claim made
by any other related party.
Return authorization must be obtained from Sealevel Systems before returned
merchandise will be accepted. Authorization can be obtained by calling Sealevel
Systems and requesting a Return Merchandise Authorization (RMA) Number.
Sealevel Systems Incorporated
P.O. Box 830
155 Technology Place
Liberty, SC 29657 USA
[phone] FAX [phone]
E-mail: [e-mail]
Internet: www.sealevel.com

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Sealevel Systems Latch-16 Page 7
LATCH-16™ Relay Output Interface is a Trademark of Sealevel Systems Incorporated.
IBM, "XT" and "AT" are trademarks of the International Business Machines Corporation.