What really happens when you fax (1 of many)

Class 1

(a quick editorial comment. Duncan wrote this, primarily to get familiar with what happens during faxing so he could answer questions in the newsgroup. Oddly enough, this venture made him decide to stay away from faxing, and we haven't seen him in the fax newsgroup since.)

The CCITT TR29.2 committee accepted the Class 1 standard for faxing in 1988. At the same time the Class 2 standard was voted on, but not accepted. Some software and hardware manufacturers then unofficially adopted the Class 2 standard. Since the unofficial Class 2 standard was so widely used, the CCITT TR29.2 committee declared the official Class 2 standard would be designated as Class 2.0.

In the Class 1 standard, most of the work of sending the fax is done by the application. In class 2 and 2.0, the modems handle a large part of the negotiation.

In this tech tip, I will focus on the Class 1 standard (Class 2 and Class 2.0 will be visited in later documents).

Before getting into the details of a Class 1 fax transmission, here are a few quirks about faxing to keep in mind.

The only time you are operating at the requested baud rate is when the training data is sent and during page transmissions. For the negotiations, other baud rates (usually 300 baud) are used.

Carrier will not be maintained for the entire duration. It is dropped and restarted frequently during a fax. This means that the DCD line is not relevant.

The traditional lines (RTS, CTS, etc) used in serial communications either have no meaning or may have different meanings in faxing.

The receiver is not required t respond while page data is being sent.

Error checking is minimal at best.

These quirks in the faxing protocol can lead to some rather interesting behavior. Since carrier is dropped and raised many times during a fax session and is not actually required during the page send, you can end up with a situation in which the connection has dropped and the sender keeps on sending the fax with no way of realizing what happened.

Sending a fax

The process of sending a fax using the Class 1 standard can be broken into six steps: configuring your modem for faxing, dialing, negotiation, sending a page, ending the page, and hanging up.

Configuring your modem for faxing

To set up your fax to send or receive according to the class 1 standard, you need to send the command:

AT+FCLASS=1

Dialing

After setting the fax class, the dialing is accomplished by sending the ATDTxxxxx command. When you dial with the intention of faxing, it will automatically assume a baud rate of 300 baud. This is the rate that is used for negotiating the fax.

Negotiation

In the negotiation stage, things are starting to get a little tricky. Once the connection is made, the remote fax will send the NSF frame. The NSF frame contains user requirements that are not part of the fax class 1 standard. After receiving the NSF frame, the sender will send the AT+FRH=3 command.

The +FRH and +FTH (receive and transmit HDLC) commands are used for negotiating the fax session. The parameter specified on the command determines the baud rate that will be used as well as the training time required and some assumptions about the hardware involved.

+FRH= value	Baud Rate
3	300
24	2400
48	4800
72	7200
96	9600
121	12000
145	14400

Not all fax machines are required to support all the baud rates. Only the lower ones are required. The normal baud rate for the negotiations is 300 baud, so you will see +FRH=3 and +FTH=3 more any of the other values.

When the +FRH command is sent, the carrier is dropped (you may receive a NO CARRIER from the modem at this point) and is raised again at the new baud rate (You should receive a CONNECT from the modem at this point). In addition, the +FRH command tells the other end that it should send some information. There is now parameter to +FRH that indicates what information should be sent. What you get depends on where you are in the faxing process.

After the AT+FRH=3 command is sent in response to receiving the NSF frame, the remote fax will then send the CSI (Call Station ID) frame. This frame is transmitted backwards. The local fax will send AT+FRH=3 again causing the remote fax to send the DIS (Digital Identification Signal) frame. The DIS frame contains a bitmask that describes the capabilities of fax sender and receiver. The contents of the DIS frame are:

Bit Number	Meaning
1	Transmitter T.2 Operation
2	Receiver T.2 Operation
3	T.2, IOC = 176
4	Transmitter T.3 Operation
5	Receiver T.3 Operation
6-8	Reserved for future T.3 features
9	Transmitter RS 465 Operation
10	Receiver RS 465 Operation
11-12	Baud Rate
	0, 0	2400 baud
	0, 1	4800 baud
	1, 0	7200 baud
	1, 1	9600 baud
13-14	Reserved
15	Vertical resolution is 7.7 lines per millimeter
16	Two-dimensional coding capability
17	Maximum paper width is 256mm
18	Maximum paper width is 297mm
19	Maximum paper width is 364mm
20	Unlimited paper length
21-23	Scan time
	0,0,0	20msec
	0,0,1	40msec
	0,1,0,	10msec
	0,1,1	5msec
	1,0,0	10msec
	1,0,1	20msec
	1,1,0	40msec
	1,1,1	0msec (APRO uses this)
24	Extend field
25	2400 baud handshaking
26	Uncompressed data
27-31	Unassigned
32	Extend field

At this point, we will transmit the AT+FTH=3 which will cause the remote fax to drop the carrier twice. The modem will reply with CONNECT when it is time for us to send the information. The first time we will send the TSI frame. The second time we will send the DCS frame. After the last frame has been sent, we will send the AT+FTS=8 (fax transmit silence – it will transmit 80ms of silence) command. This command will drop the carrier and wait 80ms.

After waiting 80ms, we can send the training data. This is just a series of NULLS lasting for 1.5 seconds plus or minus 10%. The AT+FTM=xx command is sent to drop the carrier and negotiate a new baud rate (this takes the same parameter for the baud rate as the +FRH command) and after the modem returns “CONNECT”, the training data is sent. The baud rate used here is the same baud rate that will be used to send the data.

After the training data has been sent, the AT+FRH=3 command is sent again and then we get the CFR frame.

Sending a page

Finally, after all the negotiations, we can send a page of the fax. Compared to the fax negotiation, this is easy.

First we will send the AT+FTM=xx command to drop the carrier and negotiate the baud rate. After the modem replies with CONNECT, and we can transmit the page.

Ending the page

After the page has been sent, send the AT+FTS=8 command to wait 80ms and then the AT+FTH=3 command to drop the drop the speed to 300 baud. When we get the “CONNECT” response from the modem, we can send the end of page frame.

After sending the last line of a page frame, we send the AT+FRH=3 command so that we can receive the MCF frame. The MCF frame is the receiver telling the sender whether it received the page successfully or not. Once we have received that frame, we send the AT+FTH=3 command, when the modem responds with “CONNECT”, we can send the DCN frame.

The “Sending a page” and “Ending a page” steps will be performed for each page of the fax.

Hanging up

This is probably the easiest step of the entire process. Just send the ATH0 command to the modem to hang it up.

Receiving a fax

Receiving a fax is very similar to the sending process. Again, it can be broken into six steps: configuring your modem for faxing, answering, negotiation, receiving a page, ending the page, and hanging up.

Configuring your modem for faxing

This step is the same as it is for sending a fax, send the AT+FCLASS=1 command to your modem.

Answering

After configuring your modem for Class 1 faxing, answering the call is just like answering a data call. APRO will wait for a “RING” response from the modem indicating an incoming call. It will then send the ATA command to tell the modem to answer the call.

Negotiation

As with sending, when the connection is made, we will assume it was made at 300 baud. We will send the NSF frame and drop and the modem to connect twice. The first reconnect, we will send the CSI frame, the second we will send the DSI frame.

After sending the required frames, send the AT+FRH=3 and receive the TSI frame. Send the AT+FRH=3 command again, and send the DCS frame.

Now, we can send the AT+FRM=xx command to set the baud rate for receiving the training data. Wait for the CONNECT; when we get it, it will be followed by the training data, then the carrier will drop. Once that happens, Send the AT+FTH=3 command, and send the CFR frame.

Receiving a page

Receiving a page is fairly simple. Send the AT+FRM=xx command to receive data. The data will follow once the modems reconnect. After the page is sent, the carrier will drop.

Ending the page

Once the carrier drops after receiving a page, send the AT+FRH=3 command and wait for the EOP frame. Once the EOP frame has been received, send the AT+FTH=3 command and send the MCF frame. After that, send the AT+FRH=3 command and wait for the DCN frame.

Hanging up

This is probably the easiest step of the entire process. We send the ATH0 command to the modem to hang it up.

Summary of Class 1 fax commands

Here is a summary of all the commands used by the Class 1 faxing standard.

+FCLASS

The +FCLASS command is used for inquiring and setting the fax class.

If you call it with an AT+FCLASS?, the modem will return the current state of the modem. For example, a return value of 1 indicates the modem is ready for Class 1 faxing.

Response	Meaning
0	Data Modem
1	Class 1
1.0	Reserved
2	Manufacturer specific (Class 2)
2.0	Class 2.0
4	Reserved
8	Voice DCE

If you call it with an AT+FCLASS=?, the modem will return a comma separated list of supported fax classes. For example, a modem might return “0,1” to indicate data and class 1 faxing.

The AT+FCLASS=x value will set the modem to use the specified fax class.

+FTS and +FRS

The +FTS and +FRS commands will transmit and receive silence respectively. They take a single parameter that specifies the tens of milliseconds of silence that is expected. For example, AT+FTS=8 will transmit 80ms of silence. After transmitting silence, an OK is returned from the modem. When receiving silence, an OK will be returned only if the expected amount of silence is heard on the line.

+FTH and +FRH

These commands are used at 300 baud to handle all the negotiation between the two faxes.

The +FTH command will cause data framed in the HDLC protocol to be transmitted at the baud rate specified. The end of the data transmitted is indicated by the <DLE><ETX> characters.

+FRH= value	Baud Rate
3	300
24	2400
48	4800
72	7200
96	9600
121	12000
145	14400

The +FRH command will receive data framed in the HDLC protocol at the specified baud rate.

+FTM and +FRM

The +FTM and +FRM commands transmit and receive the fax respectively. They will set the baud rate to the parameter specified (AT+FRM=96 to receive a fax at 9600 baud). The <DLE> <ETX> characters will indicate the end of the data. After the fax as has finished, the carrier will be dropped.

There is really no error checking at all while the page is sending or being received.

+FCERROR and +F4

The +FCERROR is used to indicate when a carrier other than what is expected on a +FTM, +FRM, +FTH or +FRH command is found.

+FMI, +FMM and +FMR

The +FMI, +FMM and +FMR commands are used to request information about the modem. AT+FMI? will request the manufacturer, AT+FMM? will request the model, and AT+FMR? will request the revision number. The commands are optional and are not supported on all modems.

+FLO

The +FLO is an optional command used to set the flow control. It takes a single parameter that indicates the flow control:

+FLO=x value	Meaning
0	Turn off XON/XOFF and 133/106 flow control
1	Use XON/XOFF flow control
2	Use CCITT Circuit 133 and 106 for flow control

For example, AT+FLO=0 would turn XON/XOFF off. +FLO is not supported on all modems and +FLO=2 is very optional.

+FPR

The +FPR command allows the baud rate to be fixed at a specific rate. This command can be given at the same time as the +FCLASS=1 command. The command may not be supported on all modems.

+FPR Value	Baud Rate
0	Autobaud (includes 9600 and 19200)
1	2400
2	4800
4	9600
8	19200
10	38400
18	57600

Example: +FPR=0 to set the baud rates to be automatically determined.

How does this show up in the dispatch log?

Now that we have covered the theory, let’s see how the faxing process works from the point of the dispatch log. You can generate a dispatch log by setting the Logging property of your port to tlOn and then specifying an explicit path and file name for you LogName property. For faxing, the default log size is too small; you will need to adjust it up (add a couple of zeros to the end of the log size – that should suffice).

In the dispatch logs, the various states of the faxing process are shown on the dispatch log lines with a type field of “Fax”. Fax class 1 receiving states start with “rf1” and fax class 1 transmitting states start with “tf1”. The full list of the fax subtypes is in the AwFax.pas unit.

Receiving a fax

APRO v3.03

Compiler : Delphi 5

Operating System : Windows NT 5.0

Time      Type      SubType       Data      OtherData

--------  --------  ------------  --------  ---------

0000.012  TrDatChg  Avail         00000001

0000.013  TrgHdAlc  Window        003A0326

0001.032  User                    00000000  Receive_one_page,_Class1

0001.032  TrDatChg  Avail         00000001

0001.032  TrigAllc  Timer         00000008

0001.032  TrigAllc  Timer         00000010

0001.032  TrigAllc  Status        0000001B  (Output buffer free)

0001.032  TrigAllc  Status        00000024  (Output buffer used)

0001.032  TrigAllc  Status        00000029  (Modem status)

The default INIT string sent before all faxes.  If you have a custom modem init,

it would show up before this one.

0001.132  Dispatch  WriteCom      00000001  A

0001.132  Dispatch  WriteCom      00000001  T

0001.132  Dispatch  WriteCom      00000001  E

0001.132  Dispatch  WriteCom      00000001  0

0001.132  Dispatch  WriteCom      00000001  Q

0001.132  Dispatch  WriteCom      00000001  0

0001.132  Dispatch  WriteCom      00000001  V

0001.132  Dispatch  WriteCom      00000001  1

0001.132  Dispatch  WriteCom      00000001  X

0001.132  Dispatch  WriteCom      00000001  4

0001.132  Dispatch  WriteCom      00000001  S

0001.133  Dispatch  WriteCom      00000001  0

0001.133  Dispatch  WriteCom      00000001  =

0001.133  Dispatch  WriteCom      00000001  0

0001.133  Dispatch  WriteCom      00000001  S

0001.133  Dispatch  WriteCom      00000001  2

0001.133  Dispatch  WriteCom      00000001  =

0001.133  Dispatch  WriteCom      00000001  4

0001.133  Dispatch  WriteCom      00000001  3

0001.133  Dispatch  WriteCom      00000001  [0D]

0001.133  TrDatChg  Timer         00000008  [B6][00][00][00]

0001.133  TrDatChg  Timer         00000008  [B6][00][00][00]

0001.149  Dispatch  ReadCom       00000006  [0D][0A]OK[0D][0A]

Set fax class 1

0001.251  Dispatch  WriteCom      00000001  A

0001.251  Dispatch  WriteCom      00000001  T

0001.251  Dispatch  WriteCom      00000001  +

0001.251  Dispatch  WriteCom      00000001  F

0001.251  Dispatch  WriteCom      00000001  C

0001.251  Dispatch  WriteCom      00000001  L

0001.251  Dispatch  WriteCom      00000001  A

0001.251  Dispatch  WriteCom      00000001  S

0001.251  Dispatch  WriteCom      00000001  S

0001.251  Dispatch  WriteCom      00000001  =

0001.251  Dispatch  WriteCom      00000001  1

0001.252  Dispatch  WriteCom      00000001  [0D]

0001.252  TrDatChg  Timer         00000008  [B6][00][00][00]

0001.252  TrDatChg  Timer         00000008  [B6][00][00][00]

0001.262  Dispatch  ReadCom       00000006  [0D][0A]OK[0D][0A]

Find out what receive modes the modem supports?

0001.475  Dispatch  WriteCom      00000001  A

0001.475  Dispatch  WriteCom      00000001  T

0001.475  Dispatch  WriteCom      00000001  +

0001.475  Dispatch  WriteCom      00000001  F

0001.475  Dispatch  WriteCom      00000001  R

0001.475  Dispatch  WriteCom      00000001  M

0001.475  Dispatch  WriteCom      00000001  =

0001.475  Dispatch  WriteCom      00000001  ?

0001.475  Dispatch  WriteCom      00000001  [0D]

In this case we support 300 baud, 2400 up to 14400.

0001.475  TrDatChg  Timer         00000008  [B6][00][00][00]

0001.487  Dispatch  ReadCom       0000000E  [0D][0A]3,24,48,72,7

0001.494  Dispatch  ReadCom       0000000E  3,74,96,97,98,

0001.503  Dispatch  ReadCom       0000000E  121,122,145,14

0001.509  Dispatch  ReadCom       00000009  6[0D][0A][0D][0A]OK[0D][0A]

0001.509  TrgHdAlc  Procedure     00000000

0001.509  Fax       rfInit        00000000

We reset the fax class as a safeguard

0001.612  Dispatch  WriteCom      00000001  A

0001.612  Dispatch  WriteCom      00000001  T

0001.612  Dispatch  WriteCom      00000001  +

0001.612  Dispatch  WriteCom      00000001  F

0001.612  Dispatch  WriteCom      00000001  C

0001.612  Dispatch  WriteCom      00000001  L

0001.612  Dispatch  WriteCom      00000001  A

0001.612  Dispatch  WriteCom      00000001  S

0001.613  Dispatch  WriteCom      00000001  S

0001.613  Dispatch  WriteCom      00000001  =

0001.613  Dispatch  WriteCom      00000001  1

0001.613  Dispatch  WriteCom      00000001  [0D]

0001.613  TrDatChg  Timer         00000008  [B6][00][00][00]

0001.613  TrDatChg  Timer         00000008  [B6][00][00][00]

0001.613  TrDatChg  Timer         00000010  [12][00][00][00]

0001.624  Dispatch  ReadCom       00000006  [0D][0A]OK[0D][0A]

0001.624  Trigger   Avail         00000006

0001.624  Fax       rf1Init1      00000000

0001.624  Fax       rf1Init1      00000000

Wait for the phone to ring

0001.624  TrDatChg  Timer         00000008  Deactivated

0002.627  Trigger   Timer         00000010

0002.627  Fax       rfWaiting     00000000

0002.627  TrDatChg  Timer         00000010  [12][00][00][00]

0003.680  Trigger   Timer         00000010

...

0071.644  TrDatChg  Timer         00000010  [12][00][00][00]

0072.647  Trigger   Timer         00000010

0072.647  Fax       rfWaiting     00000000

0072.647  TrDatChg  Timer         00000010  [12][00][00][00]

0073.700  Trigger   Timer         00000010

0073.700  Fax       rfWaiting     00000000

0073.700  TrDatChg  Timer         00000010  [12][00][00][00]

0074.590  Dispatch  ReadCom       00000008  [0D][0A]RING[0D][0A]

0074.590  Trigger   Avail         00000008

0074.590  Fax       rfWaiting     00000000

0074.590  Fax       rfWaiting     00000000

0074.590  TrDatChg  Timer         00000008  [B6][00][00][00]

0074.590  Fax       rfWaiting     00000000

0074.590  Fax       rfWaiting     00000000

0074.590  TrDatChg  Timer         00000008  [B6][00][00][00]

We got a ring, tell the modem to answer the call.

0074.590  Fax       rfAnswer      00000000

0074.690  Dispatch  WriteCom      00000001  A

0074.690  Dispatch  WriteCom      00000001  T

0074.690  Dispatch  WriteCom      00000001  A

0074.690  Dispatch  WriteCom      00000001  [0D]

0074.690  TrDatChg  Timer         00000008  [B6][00][00][00]

0074.690  TrDatChg  Timer         00000008  D[04][00][00]

0074.740  Trigger   Timer         00000010

Every second, we have a status timer that fires.  You can see

here that it’s taken 5 seconds to see that there is a fax on the other end.

0074.740  Fax       rf1SendCSI    00000000

0074.740  TrDatChg  Timer         00000010  [12][00][00][00]

0075.793  Trigger   Timer         00000010

0075.793  Fax       rf1SendCSI    00000000

0075.794  TrDatChg  Timer         00000010  [12][00][00][00]

0076.847  Trigger   Timer         00000010

0076.847  Fax       rf1SendCSI    00000000

0076.848  TrDatChg  Timer         00000010  [12][00][00][00]

0077.902  Trigger   Timer         00000010

0077.902  Fax       rf1SendCSI    00000000

0077.902  TrDatChg  Timer         00000010  [12][00][00][00]

0078.956  Trigger   Timer         00000010

0078.956  Fax       rf1SendCSI    00000000

0078.956  TrDatChg  Timer         00000010  [12][00][00][00]

0079.959  Trigger   Timer         00000010

0079.959  Fax       rf1SendCSI    00000000

0079.959  TrDatChg  Timer         00000010  [12][00][00][00]

The local fax acknowledges that the remote is a fax and generates a “CONNECT”.

0080.163  Dispatch  ReadCom       0000000B  [0D][0A]CONNECT[0D][0A]

0080.163  Trigger   Avail         0000000B

We send the CSI frame (Call Station ID) property.  It is sent backwards.

In this case we sent “MY STATION ID”.  It is padded to 20 characters and

ends with an “C” followed by an ETX (0x03) and an 0xFF.

0080.163  Fax       rf1SendCSI    00000000

0080.163  Fax       rf1SendCSI    00000000

0080.183  Dispatch  WriteCom      00000001  [FF]

0080.183  Dispatch  WriteCom      00000001  [03]

0080.183  Dispatch  WriteCom      00000001  C

0080.183  Dispatch  WriteCom      00000001  [20]

0080.183  Dispatch  WriteCom      00000001  [20]

0080.183  Dispatch  WriteCom      00000001  [20]

0080.183  Dispatch  WriteCom      00000001  [20]

0080.183  Dispatch  WriteCom      00000001  [20]

0080.183  Dispatch  WriteCom      00000001  [20]

0080.183  Dispatch  WriteCom      00000001  [20]

0080.183  Dispatch  WriteCom      00000001  D

0080.184  Dispatch  WriteCom      00000001  I

0080.184  Dispatch  WriteCom      00000001  [20]

0080.184  Dispatch  WriteCom      00000001  N

0080.184  Dispatch  WriteCom      00000001  O

0080.184  Dispatch  WriteCom      00000001  I

0080.184  Dispatch  WriteCom      00000001  T

0080.184  Dispatch  WriteCom      00000001  A

0080.184  Dispatch  WriteCom      00000001  T

0080.184  Dispatch  WriteCom      00000001  S

0080.184  Dispatch  WriteCom      00000001  [20]

0080.184  Dispatch  WriteCom      00000001  Y

0080.184  Dispatch  WriteCom      00000001  M

0080.184  Dispatch  WriteCom      00000001  [10]

0080.184  Dispatch  WriteCom      00000001  [03]

0080.184  TrDatChg  Timer         00000008  [B6][00][00][00]

The modems will reconnect after the CSI frame was sent.

0081.037  Trigger   Timer         00000010

0081.037  Fax       rf1SendDIS    00000000

0081.037  TrDatChg  Timer         00000010  [12][00][00][00]

0082.045  Dispatch  ReadCom       0000000B  [0D][0A]CONNECT[0D][0A]

0082.045  Trigger   Avail         0000000B

Now we send the DIS (Digital Identification Signal) frame.  The DIS

is a bitmask that describes what our capabilities are. This is not reversed.

0082.045  Fax       rf1SendDIS    00000000

0082.045  Fax       rf1SendDIS    00000000

0082.066  Dispatch  WriteCom      00000001  [FF]

0082.066  Dispatch  WriteCom      00000001  [13]

0082.066  Dispatch  WriteCom      00000001  [80]

0082.066  Dispatch  WriteCom      00000001  [00]

0082.066  Dispatch  WriteCom      00000001  N

0082.066  Dispatch  WriteCom      00000001  [F9]

0082.066  Dispatch  WriteCom      00000001  [00]

0082.066  Dispatch  WriteCom      00000001  [10]

0082.066  Dispatch  WriteCom      00000001  [03]

0082.066  TrDatChg  Timer         00000008  [B6][00][00][00]

0082.066  Trigger   Timer         00000010

0082.066  Fax       rf1SendDIS    00000000

0082.066  TrDatChg  Timer         00000010  [12][00][00][00]

We get an OK after sending the DIS frame

0082.463  Dispatch  ReadCom       00000006  [0D][0A]OK[0D][0A]

0082.463  Trigger   Avail         00000006

0082.463  Fax       rf1SendDIS    00000000

0082.463  Fax       rf1SendDIS    00000000

We send an AT+FRH=3 to set the baud rate to 300 and receive HDLC data.

0082.906  Dispatch  WriteCom      00000001  A

0082.906  Dispatch  WriteCom      00000001  T

0082.908  Dispatch  WriteCom      00000001  +

0082.908  Dispatch  WriteCom      00000001  F

0082.908  Dispatch  WriteCom      00000001  R

0082.908  Dispatch  WriteCom      00000001  H

0082.908  Dispatch  WriteCom      00000001  =

0082.908  Dispatch  WriteCom      00000001  3

0082.908  Dispatch  WriteCom      00000001  [0D]

0082.908  TrDatChg  Timer         00000008  [B6][00][00][00]

0082.908  TrDatChg  Timer         00000008  6[00][00][00]

0083.109  Trigger   Timer         00000010

0083.109  Fax       rf1CollFrms   00000000

0083.109  TrDatChg  Timer         00000010  [12][00][00][00]

We have connected at 300 baud, so the modem sends a “CONNECT”.

0083.285  Dispatch  ReadCom       0000000B  [0D][0A]CONNECT[0D][0A]

0083.285  Trigger   Avail         0000000B

0083.285  Fax       rf1CollFrms   00000000

0083.285  Fax       rf1CollFrms   00000000

0083.286  TrDatChg  Timer         00000008  [B6][00][00][00]

We start getting HDLC data.  In this case we get the remotes

station ID: “Kl   719 260 7151“.  Again this is backwards and

ends with the “C” ETX 0xff.

0083.662  Dispatch  ReadCom       00000001  [FF]

0083.662  Trigger   Avail         00000001

0083.662  Fax       rf1CollFrms   00000000

0083.662  Fax       rf1CollFrms   00000000

0083.689  Dispatch  ReadCom       00000001  [03]

0083.689  Trigger   Avail         00000001

0083.689  Fax       rf1CollFrms   00000000

0083.689  Fax       rf1CollFrms   00000000

0083.716  Dispatch  ReadCom       00000001  C

0083.716  Trigger   Avail         00000001

0083.716  Fax       rf1CollFrms   00000000

0083.716  Fax       rf1CollFrms   00000000

0083.742  Dispatch  ReadCom       00000001  1

0083.742  Trigger   Avail         00000001

0083.742  Fax       rf1CollFrms   00000000

0083.742  Fax       rf1CollFrms   00000000

0083.769  Dispatch  ReadCom       00000001  5

0083.769  Trigger   Avail         00000001

0083.769  Fax       rf1CollFrms   00000000

0083.769  Fax       rf1CollFrms   00000000

0083.796  Dispatch  ReadCom       00000001  1

0083.796  Trigger   Avail         00000001

0083.796  Fax       rf1CollFrms   00000000

0083.796  Fax       rf1CollFrms   00000000

0083.822  Dispatch  ReadCom       00000001  7

0083.822  Trigger   Avail         00000001

0083.822  Fax       rf1CollFrms   00000000

0083.822  Fax       rf1CollFrms   00000000

0083.849  Dispatch  ReadCom       00000001  [20]

0083.849  Trigger   Avail         00000001

0083.849  Fax       rf1CollFrms   00000000

0083.849  Fax       rf1CollFrms   00000000

0083.876  Dispatch  ReadCom       00000001  0

0083.876  Trigger   Avail         00000001

0083.876  Fax       rf1CollFrms   00000000

0083.876  Fax       rf1CollFrms   00000000

0083.902  Dispatch  ReadCom       00000001  6

0083.902  Trigger   Avail         00000001

0083.902  Fax       rf1CollFrms   00000000

0083.902  Fax       rf1CollFrms   00000000