FS-8700-101_Setra Model 370 Digital Pressure Gage Manual | Page 6 of 23 |
3.1.Hardware Connection Tips / Hints
The following notes are extracted from the Setra 370 Operator Manual.
The Setra Digital Pressure Gage implements the majority of the RS-232 communications standard, but does not provide handshaking lines (such as busy, DSR, or DTR). The four lines which must be connected are diagrammed below, along with the pin layout of the female connector on the back of the gage.
13 | 7 | 3 2 | 1 |
O O O O O O O O O O O O O |
O O O O O O O O O O O O | |
25 | | 14 | |
Pin | Desc. | | |
1Protective ground
2Input to gage (RXD)
3Output from gage (TXD)
7Signal ground
The Model 370 serial interface is a DCE (Data Communications Equipment) type, with a standard female DB25S pin connector. This means that it receives data on pin 2 and sends data on pin 3. This is in contrast to DTE (Data Transmission Equipment) which receives data on pin 3 and sends data on pin 2. The RS-232 standard describes communications between DTE and DCE devices.
Since many computers have serial ports configured as DTE, the Model 370 conveniently plugs directly into the standard serial port on most computers, using a standard RS-232 "straight-through" cable available from SETRA, or from any computer hardware vendor. Some devices, including some printers and computers, will be equipped with DCE interfaces like that in the Model 370. To connect the Model 370 to these devices, a "null modem" cable is required. This is simply a cable which connects pin 2 and 3 of the Model 370 to pin 3 and 2 of the other device respectively by crossing them in the cable. This kind of cable is also available from SETRA, or from any computer hardware vendor.
The maximum recommended cable length is 15 meters.
The RS-232 data format used by the Model 370 is: 8 bits, 1 start bit, 1 stop bit, no parity.
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