I would include a series resistor to be safe, but in previous discussing
with TS tech support regarding the DIO lines, this was communicated to me:
"Do we need to model the impedance presented by DIO_0 (configured for
input) differently than just a simple pull-up resistor to get the
correct results? Or could this indicate that this port is damaged in
some way?" - me
"No, you do not even need a pull up resistor, the EP9302 has one
internally. The port may be damaged, or you may have a high impedance
trace that you are not seeing on your custom board." - Kris Bahnsen
So, apparently, one is not required.
Don
On 10/13/2011 9:43 PM, Mike Dodd wrote:
The TS-7250 manual says, about the DIO port, "When these DIO pins are
configured as outputs, they can source 4 mA...."
Are these pins protected against a direct connection to ground when
configured as outputs? I.e., is there an internal resistor or
current-limiter on each pin?
I have an application that interfaces the 7250 to an HVAC system,
using its 24VAC signals to control dry-contact relays wired to the DIO
port.
Since the HVAC can actuate these relays at any time, I'm concerned
that one or more might be connecting the DIO pin to ground when the
7250 is powered-on, before my program launches and configures the pins
as inputs. This will be only a brief period, but I don't want to take
a chance of zapping the DIO port.
Am I safe, or should I include a series resistor to the relay contact?
Thanks.
--- Mike
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