S3-1: Receive Impedance
The setting for switch S3-1 selects the impedance of the input receiver. You may select either a “low” impedance of 120 Ohms or a “high” impedance of 16K Ohms. By selecting the proper impedance for each drop, there may be up to 50 receivers in one application.
S3-1 | Setting |
On | Low (120 Ohm) |
Off | High (16K Ohm typical) |
S3-2: RTS/CTS Delay
The setting for switch S3-2 determines the amount of delay between the time the Model 1004ABRC “sees” RTS and when it turns on CTS. Note: RTS/CTS Delay setting should be based upon trans- mission timing.
S3-2 | Setting |
On | 8 msec |
Off | no delay |
S3-3: Reserved
Switch S3-3 is reserved and must remain in the OFF position.
S3-3 | Setting |
On | Not a Valid Setting |
Off | Default Setting |
S3-4: Echo Mode
The setting for switch S3-4 determines whether the Model 1004ABRC echoes data back to the transmitting device (half-duplex mode only).
S3-4 | Setting |
On | Echo On |
Off | Echo Off |
SWITCH SET “S4”
DIP switch S4 is used to configure transmit impedance, and 2-wire/4-wire operations. The summary table below shows the factory default settings for switch S4. Following the summary table is a detailed description of each individual switch.
SWITCH S4 SUMMARY TABLE (factory defaults in bold)
Position | Function | ON Position | OFF Position |
| | | |
S4-1* | TX Impedance | Intermediate | High |
| | | |
S4-2* | TX Impedance | Intermediate | High |
| | | |
S4-3* | 2-Wire/4-Wire | 2-Wire | 4-Wire |
| | | |
S4-4* | 2-Wire/4-Wire | 2-Wire | 4-Wire |
| | | |
*Note: Switches S4-1 and S4-2 must be switched simultaneously. Switches S4-3 and S4-4 must be switched simultaneously.
S4-1 and S4-2: “Transmit Off” Impedance
Switches S4-1 and S4-2 are set together to determine whether the receiving device “sees” the impedance of the Model 1004ABRC’s trans- mitter as being “high” or “intermediate” when the transmitter is turned off. The “intermediate” setting is useful in half-duplex environments where the receiving device does not respond well to the “high” setting.
S4-1 | S4-2 | Setting |
On | On | Intermediate Impedance |
Off | Off | High Impedance |
S4-3 and S4-4: 2-wire/4-wire Modes
Switches S4-3 and S4-4 are set together to determine whether the Model 1004ABRC is in 2-wire or 4-wire operating mode. Note: 2-wire mode is half-duplex only.
S4-2 | S4-3 | Setting |
On | On | 2-wire mode |
Off | Off | 4-wire mode |
