Comtech EF Data SMS-758 - Manual (Page 66)

Theory of Operation SMS-758 Modem Protection Switch
4–6 MN/SMS758 Rev. 3
Table 4-1. Error Response Switch Options
Switch
Position
Switch Function Description
SP1-6 ER6_BUSY enable
ON = Enabled
OFF = Disabled
Selects whether the switch will return an
ER6_BUSY response if it cannot process the
received remote command. A response will not
be returned if this switch is OFF.
SP1-7 ER6_BUSY wait
ON = Immediate response
OFF = 2 second response
Selects the time the switch attempts to process
the command. ER6_BUSY enable determines if
ER6_BUSY will be returned or not. In the
immediate response mode (ON), this will be less
than 320 ms from the command response
received by the switch.
SP1-8 WAIT for Modem response
ON = 2 seconds
OFF = 4 seconds
Selects the time the switch will wait for a modem
to respond to a remote command.
Table 4-2. Software Versions for Response Switch
Software Versions
Switch Function Modem Switch Mod/Demod Switch
ER6_BUSY enable ≥
5.00
≥
6.00
ER6_BUSY wait ≥
5.09
≥
6.11
WAIT for modem response ≥
5.10
≥
6.12
4.1.8 External I/O Interrupt Arbitration
The SMS-758 switch does not use the external I/O interrupt arbitration function. JP12,
JP13, and JP14 must be in the “LEFT” position to disable this function.
4.2 Modem Control Interface Specification
The modem control interface is an RS-485 serial communication link which allows the
switch to maintain control of backup modems, and verify the configuration of the prime
and backup modems. (See Section 2.4.3 for details of connector position and pinout.)
The RS-485 interface permits up to 32 devices to operate on a common communication
link. However, only modems and channel units may be connected to this communication
link, besides this switch. External remote communication to the modems and switch is
accomplished through the external remote interface. Refer to Section 4.1.5 for more
information.
The user cannot configure the parameters of the RS-485 interface. The baud is fixed at
9600 and parity is even. All devices communicating with the switch must have their
remote control interfaces configured to those parameters. Each modem and channel unit
must have a unique address. Refer to the Installation and Operation Manuals for each
device for details of remote interface specification and configuration.