TDC3000 printer configuration

I am wondering if somebody can help me with a strange problem with TDC3000 US printer ports. We have 3 US's with 3 printer ports assigned
to them. We are currently using one of them to send data out to PC (PN1), one is connected to parallel printer via protocol changer (PN5) and another is idle(PN4). I wanted to create another data conection, similar to the one already existing, but I have run into problems. First, the idle printer port would not print out any data, nevermind how I try - by just printing a journal, using SEND in a CL code or using DO PN4 command line option. Probably the hardware is dead, however, when US4 is rebooted, some garbage shows up on the port, so it is not like completely dead. When I tried on the port with parallel printer connected to it(PN5), it will print out stuff only when I use DO PN5 on the command line, for example. Is it there some hardware or software configuration option that needs to be changed to make at least PN5 to accept printing requests, say from CL code? It is really strange to have 3 printer ports and each of them to behave in completely different way.
Thanks in advance.
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