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Sink/Source Inputs. All DC inputs in VersaMax can be used for
either sink or source. We have used them only for source. See the next
note on Source inputs for a schematic and more details.
Warning: The MSP may not function properly with
sinking Inputs.
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Source Inputs. Each input is basically a resistor with one end
of each resistor tied to individual terminals. The other ends are tied
together to a terminal that is tied to COM that is tied to +VDC. This
pull up resistance sources voltage and current from +VDC.
The output on the MSP is designed to be used as
either sink or source. The MSP contains a sinking gate and pull-up
resistor. Source inputs can be wired directly to the MSP.
Using the input as source would increase the level
of the signal and make it more immune to noise but it would double the
current required when the signal is pulled to zero volts.
Make sure that the PLC input module and MSP input
get their 24 VDC from the same source. Following is a schematic of a
typical input. "%I?" may be any valid input. In the single
channel drivers for the VersaMax Nano/Micro the input is %I1 but may
be changed if desired. In the multiplexed drivers for the VersaMax
Nano/Micro Channel 0 and 1 are %I1 and %I2 respectively but may be
changed if desired.
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Sink Inputs. Each input is basically a resistor with one end
of each resistor tied to individual terminals. The other ends are tied
together to a terminal marked "Com". This pull down
resistance sinks voltage and current to common VDC.
Warning: The MSP may not function properly with
sinking Inputs.
The output on the MSP is designed to be used as
either sink or source. The MSP contains a sinking gate and pull-up
resistor. Sink inputs can be wired directly to the MSP.
Using the input as sink puts the two resistances in
series forming a voltage divider. This causes the voltage to switch
between 0 and 12 VDC with a 24 VDC power supply. The VersaMax Nano/Micro
inputs have a specified on threshold of 15 VDC min. We found that 12
volts was not enough to reliably turn the input on and the module
would not function properly with sinking inputs. Note that even though
the LED will light it is very dim.
Make sure that the PLC input module and MSP input
get their 24 VDC from the same source. Following is a schematic of a
typical input. "%I?" may be any valid input.
Note: The true/false sense for a sourcing input
is opposite that of a sinking input. In ladder logic the hardware
input into the driver must be normally open to provide the proper
logic sense.
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Relay Outputs. Relay outputs can be used as either sink or
source. We have used them only for source. See the next note on
Sourcing outputs for a schematic and more details. The model used for
testing had only one DC output so we had to slow the output driver
down in order to debug the multi-channel output drivers and not
destroy the relay. I used a scan time of 30 msec for the MSP analog
output modules.
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Output on Demand. In order to conserve the life of the relay
output the output drivers contain some extra logic that allows control
of when the output is transmitted. There are two bits for the user to
access for this control.
The first bit "Out Demand Continuous" when turned on will
cause the output to transmit continuously. When this bit is turned off
the driver will complete the current transmission and then will
remaining off. The continuous transmission bit has been forced on by
ladder logic by default but may be edited if desired.
The second bit "Out Demand Single" causes the output to
transmit one time. Only the off to on transition of this bit will
cause a transmission. The continuous transmission bit takes priority
over the single transmission bit. The continuous transmission bit must
be turned off in order to use the single transmission bit. It is
recommended that if the single transmission bit is use that the Delta
Refresh Count Preset be set to zero (0). When the Delta Refresh Count
Preset is set to zero (0) the full 16 bit value will be transited
every time and the delta transmission is effectively turned off.
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Input/Output Scan Time Ratio. For those drivers using relay
outputs there is logic that runs the output a factor of 3 times slower
than the input. This allows the program scan and inputs to run at a
scan time of 10 msec and the output to run a scan time of 30 msec.
This is necessary only when relay outputs must be used.
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Source Outputs. Currently only Source DC outputs are available
on the VersaMax Nano/Micro. Each output is basically a transistor or
contact with one end of each transistor tied to individual terminals.
The other ends are tied together to a terminal that is usually labeled
either V1 and connected to +VDC. This pull up transistor or relay
sources voltage and current from +VDC. The DC Outputs also require a
reference connection to –VDC usually on terminal C1.
The input on the MSP is sink; it is basically a
resistor tied to -VDC or common. Source outputs can be wired directly
to the MSP.
Make sure that the PLC output module and MSP output
get their 24 VDC from the same source. Following is a schematic of a
typical output. "%Q?" may be any valid output. In the single
channel drivers the output is %Q 1 but may be changed if desired. In
the multiplexed drivers Channel 0 and 1 are %Q 1 and %Q 2 respectively
but may be changed if desired.
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Sink Outputs. Each output is basically a contact with one end
of each contact tied to individual terminals. The other ends are tied
together to -VDC. This pull down contact sinks voltage and current to
-VDC.
The input on the MSP is sink; it is basically a
resistor tied to -VDC or common. Since both PLC output and MSP are
sink a pull up resistor must be used. Sink outputs can be wired
directly to the MSP with a pull-up resistor.
Make sure that the PLC output module and MSP output
get their 24 VDC from the same source. Following is a schematic of a
typical output. "O?" may be any valid output.
Note: The true/false sense for sinking outputs
is opposite that of the sourcing outputs. In ladder logic the hardware
output from the driver must be negated before going to the hardware
output to provide the proper logic sense.
