New S7-1200 on the line 2 filler, 1215C DC/DC/DC, firmware 4.4 on the label, CPU in RUN. KEPServerEX 6.x with the Siemens TCP/IP Ethernet driver, model S7-1200, port 102. Channel and device both show connected in the server status bar.

Every tag comes up Bad quality, 30 of them, all in DB1. The same server and the same driver read a 315-2 PN/DP on line 1 without a problem. The event log says "Device 'Line2.Filler' read request failed, block DB1", roughly. Ping's fine, I rebooted the server box and rebuilt the device with rack 0 slot 1 and then rack 0 slot 0, no change, and DB1 isn't optimized, I checked the block properties.

What's different about the 1200 that the 300 doesn't care about? Pretty sure it's something on the CPU side and not the server, because the 315 reads all day off the same box.