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How do you implement reliable power-up/power-down of serial (rs232/rs422) communication?
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valentin tihomirov
Apr 30, 2003, 4:17:15 AM4/30/03
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Hello,
my host computer continously listenning rs232 and rs422 serial ports. I face
a problem during powering my attached device to that port. That is the host
raises a communication error. Host detects rs232 error only when the device
is powered after long period in down (>10 seconds). When the device is
connected to host via rs422 driver the host software fails during both
power-up and power-down of the device. The driver chips I use (max3221,
max3238 for rs232 and max3491, max3490 for rs422) have always their drivers
(outputs to the host) enabled. Some of the chips even don't have DE(driver
enabling pin) to disable the driver. The driver inputs are connected to
open-collector pins of MCU, that is the default state of the pins is 1
(during power-up and reset). This HIGH means OK serial idle state.
Have you faced the same problems and how did you resolve it?
my host computer continously listenning rs232 and rs422 serial ports. I face
a problem during powering my attached device to that port. That is the host
raises a communication error. Host detects rs232 error only when the device
is powered after long period in down (>10 seconds). When the device is
connected to host via rs422 driver the host software fails during both
power-up and power-down of the device. The driver chips I use (max3221,
max3238 for rs232 and max3491, max3490 for rs422) have always their drivers
(outputs to the host) enabled. Some of the chips even don't have DE(driver
enabling pin) to disable the driver. The driver inputs are connected to
open-collector pins of MCU, that is the default state of the pins is 1
(during power-up and reset). This HIGH means OK serial idle state.
Have you faced the same problems and how did you resolve it?
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