We have problems to connect the CR300 (and CR1000) RS232 port to this RS232 to opto-isolated RS485/422 converter:
https://www.commfront.com/products/industrial-opto-isolated-port-powered-rs232-to-rs485-rs422-converter?variant=9208529667
We have a pair of these converters. When we put them back to back together (using RS422) and connect both RS232 ends to normal RS232 ports of a computer they work fine. But when we connect one end to a CR300, then the CR300 does not respond.
On the other hand, this board, intended to use with UART level RS232 works fine with both, the CR300 and CR1000.
http://www.futurlec.com/Mini_RS422.shtml
Has the RS232 port of the CR300 not true RS232 levels, but UART/TTL levels? I thought this is the case when using C1/C2 as serial interface. But not for the RS232 namend DB9 port.
Thanks for any clarifying informations.
Manuel
The CR300 does have a RS232 driver. I just measured mine. The Tx line is idling at -5.6V.
Pins 6 and 8 have 5V. Maybe that opto isolator pulls too much current.
You might be being caught out by another issue, which is that the CR300 turns off its RS232 port to save power when it is not being used. For normal comms the logger can receive characters in this mode, wake up and turn on the port. However, if your RS485 interface relies on the port for power it will never be able to wake up the logger.
It is possible to force the CR300 to turn its RS232 port on all the time. There is a setting for this you can change. It is found in the settings editor on the Advanced tab. The setting is called "RS232 Always On"
If you turn on the port all the time there will be a small increase in power drain of the logger of a few mA.
@ aps
There is no setting "RS232 Always On" in the Advanced tab of the CR300 Device configuration. (it is in the CR1000)
OS Version: CR300.Std.07.01
Is there a other OS Version?
The current release of devconfig will show the "RS232 Always On" setting in the settings editor panel as well as on the "Advanced" tab of the deployment panel. If you are running an older version of devconfig, the setting will only appear in the "Settings Editor" panel.