Omron B7A Manual page 73

B7AH
Precautions
General
Common Precautions
The B7AH performs 1-to-1 communications and does not require a
communications master. It cannot be connected to CompoBus/S
transmission paths from OMRON remote masters.
Do not use the B7AH in locations subject to corrosive gases.
When using the B7AH in locations where a large amount of static
electricity is generated (e.g., molding materials, powder, or fluid
materials conveyed along pipelines), install the B7AH at least 1 m
away from the source of the static electricity.
Line Resistance in the Transmission Path
If power and signals are transmitted together along 3-core cable,
ensure that the line resistance in the transmission path between
Link Terminals is less than 2.5 Ω. (The same value applies even if
terminal blocks, connectors, or slip rings are used at points on the
line.) If the line resistance rises to a value greater than this, the cur-
rent flowing to 0 V and the line resistance will cause a large voltage
drop, preventing normal transmission and generating an error. As a
rough guide, the line resistance with a VCTF cable of thickness
will be 2.5 Ω per 100 m.
2
0.75 mm
Connection to 10-point B7A Terminals is not possible because
transmission signals are not compatible.
If there is a possibility of shocks or vibration, prevent the pins being
damaged by securing the Link Terminal to the PCB using an (e.g.,
epoxy-based) adhesive.
Do not touch the pins. Doing so may cause deformation. In addition,
touching the pins in an ungrounded state may result in damage to
internal elements due to static discharge. Use an anti-static mat dur-
ing work to ensure that the body is in a grounded state.
Soldering
When soldering using a soldering iron or a soldering bath, solder in
less than 5 s at a temperature not exceeding 260 C. Do not use
reflow soldering.
Recommended Cables
Normal-speed Models
Cabtire Cables
With a single power supply connected to Input or Output Link Termi-
nal:
2
0.75-mm VCTF cable 3
With independent power supplies connected:
2
0.75-mm VCTF cable 2
The following cables can also be used:
Twisted-pair Cables
(If only a single power supply is used, a conductor of thickness
2
0.75-mm min. is required.)
Transmission distance: 100 m max.
High-speed Models
Shielded Cables
Use cables for which the cross-sectional area of the conductor is at
2
least 0.75 mm .
Cleaning
Do not use highly acidic or highly alkaline solvents to clean the PCB.
Power Supply
Be sure to use the specified power supply voltage. Do not use a
power supply that has a large ripple or intermittently generates
abnormal voltages.
Noise and Miswiring Protection Circuits
If there is a possibility of noise interference between the power sup-
ply pins (+V and –V or VDD and VSS) or at input or output pins (IN00
to IN15 or OUT00 to OUT15), or if there is a possibility of miswiring
the signal pin (SIG) and the positive power supply pin (+V or VDD),
include the protection circuits described on page 68.
Wiring
Do not wire transmission lines parallel to, and less than 10 cm away
from, lines carrying high voltages or currents. If transmission lines
are installed less than 10 cm away from potential sources of noise,
confirm that correct operation is possible before using the Link Ter-
minal in actual operation.
Do not perform wiring with the power supply turned ON. Doing so
may cause pins to be accidentally short-circuited, resulting in dam-
age to internal elements and communications failure.
If the SIG pin and the positive power supply pin or the VDD (+5 V)
pin are shorted during communications, the Link Terminal will mal-
function and normal communications will not be possible. Confirm
that power lines are not shorted before turning ON the power.
Be sure to apply the specified power supply to the power supply pins
(positive, negative, VDD, and VSS). Applying excessive voltages
(e.g., 100 VAC) will cause the Link Terminal to malfunction and nor-
mal communications will not be possible.
Shorting (no-load state) the OUT pins of Output Link Terminals dur-
ing communications will cause the Link Terminal to malfunction. Be
sure to connect a load within the specified load current range. When
measuring the current with a tester, measure with the load supplied.
B7AH
71