| | | Profibus-DP - finally also for humidity applications As the first provider of humidity measurement technology in the world, Testo has made the most common field bus available: Profibus-DP. This has become standard in production automation and is also often used for drying processes or in compressed air technology. Thanks to an "intermediate layer" (sandwich design), the testo 6681 can be equipped with this communication variant ex-works (Code B77) or later on site (Part no. 0554 6686). The advantage of the field bus: in addition to the measurement values, all individual reports (i.e. also the numerous self-monitoring reports) can be passed on to the connected control. The relay limit values can also be altered "from above" (see graphic on left), e.g. to suit the current production batch. | | |
| | | Analog outputs - two or optionally three The testo 6681 is also very versatile regarding its analog outputs. In addition to the type of signal (4 to 20 mA two-wire or four-wire, 0 to 1 V, 0 to 5 V, 0 to 10 V, 0 to 20 mA), the number of analog outputs can be selected when ordering. Two or three channels are available. This means, for example, that the dewpoint can also be continuously montored, in addition to the relative humidity and the temperature, without the need for complicated calculations in the control. A channel can also be simply duplicated (e.g. 2x "0 to 100 %RH") in order to control an external display separately. | | |
| | | Integrated relays (optional) Thanks to the four power relays (up to 256 VAC, 3A), assemblies of the air conditioning system can be directly switched without the "detour" via a control. At the same time, the relays can be used for local alarming or for reporting limit value violations to a superordinate system. And not least, the person responsible for the system can be called to the measurement site in time with the help of a "collective alarm" (cf. self-monitoring"). | | |