FC 202 - Remote Transfer Module Exec. Block (INIIT12)

The remote transfer module executive (EXEC IIT) block function code defines how the INIIT12 remote transfer module operates. It has a fixed block address of one (within the INIIT12 module).

 

 

 

 

Outputs:

Blk

Type

Description

1

B

Port 1 communication status:

0 = good

1 - with no alarm = error warning

1 - with alarm = port failed

2

B

Port 2 communication status:

0 = good

1 - with no alarm = error warning

1 - with alarm = port failed

3

I

Spare

4

I

Spare

5

I

Spare

6

I

Spare

 

 

 

Specifications:

Spec

Tune

Default

Type

Range

Description

S1

N

0

I

Full

Port 1 transmission start delay after transmitter turned on (msecs)

S2

N

0

I

Full

Port 1 transmitter turn off delay after transmission sent (msecs)

S3

N

0

I

Full

Port 2 transmission start delay after transmitter turned

on (msecs)

S4

N

0

I

Full

Port 2 transmitter turn off delay after transmission sent

(msecs)

S5

N

200

I

Full

Port 1 maximum transmission duration (in msecs, half

duplex only)

S6

N

200

I

Full

Port 2 maximum transmission duration (in msecs, half

duplex only)

S7

N

60

I

Full

Port 1 communication status watchdog timer (secs)

S8

N

60

I

Full

Port 2 communication status watchdog timer (secs)

S9

Y

12

I

1 - 12

Port 1 baud rate:

 

1 = 110

5 = 600

9 = 4,800

2 = 134.5

6 = 1,200

10 = 1,800

3 = 150

7 = 2,000

 

4 = 300

8 = 2,400

12 = 19,200

 

NOTE: The default baud rate can be selected by switch settings in INIIT12 firmware revisions B.1 and later.

S10

N

12

I

1 - 12

Port 2 baud rate. Same settings as S9.

S11

N

0

I

0 - 3

Port 1 data characteristics:

0 = 8 data bits, 1 stop bit, no parity

1 = 8 data bits, 1 stop bit, even parity

2 = 8 data bits, 1 stop bit, odd parity

3 = 8 data bits, 2 stop bits, no parity

S12

N

0

I

0 - 3

Port 2 data characteristics. Same settings as S11.

NOTE: Not used if port 2 enabled as diagnostic port

S13

N

0

I

0 - 1

Port 1 duplex mode:

0 = full duplex

1 = half duplex

S14

N

0

I

0 - 1

Port 2 duplex mode:

0 = full duplex

1 = half duplex

NOTE: Not used if port 2 enabled as diagnostic port

S15

N

1

I

0 - 4

Port 2 mode:

0 = port 2 not used or diagnostic port

1 = standby for port 1 (port 1 preferred)

2 = alternate to port 1 (either port acceptable)

3 = both ports used (one port is acceptable)

4 = both ports required (one port not acceptable)

S16

N

10

I

0 - 100

Percent error rate used to calculate serial channel status for the executive block digital outputs. Specification S16 is used in conjunction with S7, S8, and S15 to determine if a communication equipment failure has occurred. Communication equipment failure may lead to the action selected in S17.

S17

N

0

I

0 - 3

Action on communication equipment failure:

0 = no backup equipment available

1 = switch state of D03 (select alternate equipment)

2 = switch to redundant module

S18

N

0

I

0 - 3

Exception reporting rate (time between scans):

0 = 2.00 secs

1 = 1.00 sec

2 = 0.50 sec

3 = 0.25 sec

 

 

202.1   Applications

 

202.1.1  Serial Data Channel Operation

Function code 202 is the executive block that contains the specifications for serial data channel operation. The serial data channels can operate in either half duplex or full duplex mode. The RS-232-C serial ports are individually configurable.

 

202.1.2  Half Duplex Operation

Half duplex is the operation of a communication circuit in which each end alternates as sender and receiver. At any instant, electrical information flows in only one direction. The direction of transmission (i.e., local to remote or remote to local) alternates on the serial link. Therefore, the modem carrier and the transceiver transmitter section need to be enabled before data can be transmitted. Additionally, the transmitter needs to be disabled prior to shutting down the modem carrier after the data transmission. Finally, the primary IIT module may need to switch the antenna to the active transceiver. The INIIR01 Remote Interface requires a digital output I/O module, cabling, and a termination unit to switch external equipment in the half duplex mode. The executive block provides specifications to control external communication equipment.

 

NOTE: The digital I/O module, cabling and termination unit are optional parts of the IIR. The interface requires these optional parts for operation in half duplex mode when switching external equipment is required and in applications using redundant external communication equipment (Fig. 202-1).

 

 

S9 through S14

The executive block enables the IIT module to handle various types of communication equipment. Setting S13 (channel one) or S14 (channel two) to one enables half duplex mode. Specifications S9, S10, S11 and S12 select the transmission rate (baud), type of parity (odd or even), and number of stop bits.

 

The IIT module uses the request to send (RTS) signal to control the modem carrier. Most modems have, or may be configured to have, a carrier turn-on delay. A carrier turn-on delay provides an additional delay between the receipt of the RTS signal and the activation of the clear to send (CTS) signal. The IIT module must receive the CTS signal from the modem before it starts to transmit data.

 

S1 through S6

The RTS output of the serial port keys the modem carrier. A digital I/O module output keys the transmitter carrier. The digital output enables the transmitter carrier to be keyed ON prior to the data transmission, and keyed OFF prior to turning off the modem carrier. Specifications S1, S2, S3 and S4 set delays. Specifications S1 and S3 decide the carrier turn-on delay.  Specifications S2 and S4 set the delay between dropping the transmitter carrier and dropping the modem carrier.

 

Specifications S5 and S6 allow setting limits on the duration of the transmission. These specifications insure that each side of the INIIR01 Remote Interface has an opportunity to originate a message of its own. Figure 202-1 shows the timing of external equipment enable signals for half duplex operation.

 

Figure 202-2 illustrates redundant INIIT12 modules with control of external equipment in half duplex operation. Table 202-1 lists the possible specification settings for the EXEC IIT block for the configuration in Figure 202-1.

 

 

 

 

 

 

 

 

202.1.3  Full Duplex Operation

 

S9 through S14

Full duplex is the operation of a communication circuit in which each end of the serial link can simultaneously send and receive. There is no need to alternate the direction of transmission as in half duplex mode. Setting S13 (channel one) or S14 (channel two) to zero enables full duplex mode. Specifications S9, S10, S11 and S12 select the baud rate, type of parity and number of stop bits.

 

Figure 202-3 illustrates the INIIT12 module using dual channel, full duplex operation. Table 202-2 lists possible specification settings for the remote transfer module executive block for this configuration.

 

 

 

 

 

202.1.4  Serial Line Quality Management

 

S16

The INIIT12 module continuously monitors the quality of the serial links. Specification S16 is the percent error rate used to decide the status of serial channels. Specification S16 is used in conjunction with S7 and S8 to determine that a serial channel has failed. When the percentage of messages with errors exceeds this value for a number of seconds exceeding the S7 value for channel one or the S8 value for channel two, then the channel is considered unusable (failed). When a channel is considered unusable, a channel failure bit is set in the module status, and depending on the setting of S15, the action selected in S17 may be performed.

 

Specification S16 is also used in the calculations for serial channel quality reported in the INIIT12 executive block digital outputs. These digital outputs are updated every second. If the percentage of messages with errors on a serial channel exceeds the S16 value (high error rate threshold), then the digital block output for that channel will be one with alarm. If the percentage of messages with errors on a serial channel exceeds one fifth of the S16 value (low error rate threshold), then the digital block output for that channel will be one with no alarm. Otherwise, the digital block output for that channel will be zero with no alarm.

 

S7 and S8

A serial channel is unusable when it fails for a period of time longer than the communication status watchdog timer.  Specifications S7 (channel one) or S8 (channel two) sets the communication watchdog timer. When a channel is considered unusable, the serial channel status bit in the module status is set, and the action selected by S17 can be invoked.

 

S15 and S17

Select the action taken by the IIT module when one or both serial channels are unusable. S15 determines the role of serial port two and sets the necessary conditions for communication equipment failure. Depending on the setting of S15, either a single channel failure or a dual channel failure constitutes communication equipment failure. For example, there is a communication equipment failure when:

 

1. S15 option is 1, 2 or 3 and both channels fail.

                               or

2. S15 option is 0 or 4 and one channel fails.

 

 

If a communication equipment failure occurs, the primary module will carry out the action selected in S17. The module  resets itself if the S17 option is zero. If S17 option is one, and the (optional) digital output I/O module is installed, then digital output three will be toggled. If S17 option is two, and a backup module is available, then the primary INIIT12 module goes into secondary mode and the secondary module goes into primary mode. The primary INIIT12 module continuously attempts to establish communication on failed serial ports. If SW4 pole four is set to one enabling port two to be used as a diagnostic port, then the INIIT12 module will act as if the S15 option is zero.