jmccrohan/ethercard — comment on commit 1fee5af244b86015e8ab6121e7d8a7ea212e989b
File: examples/ds18b20_pachube/ds18b20_pachube.ino line 120
By DavyLandman:

actually you should do:

timer += 30000;

that makes sure you're at the same interval, else the timer would shift due to time it took to reach the if after the timer was already exceeded.