Hello, we are Etec Automation Oy and SIEMENS AG partner SIMATIC IPC/PG authorized workshop.

Our customer has a device C7-621 and the screen was dark, I fixed it by changing the screen element and it works as it should

Our customer has another device C7-621 and the SF led lights up and the message 551 appears on the screen. The device can be used. What could be wrong? Could you help in solving the problem, so that we could serve our customers as required by quality. Those devices are not very familiar to me, but I would like to help our customer. Our customer's equipment is controlled by a compressed air compressor and it is planned to replace it with new ones, but therefore the old equipment should still work

Best regards

Pekka Vauhkonen